Abstract:

A direct-type backlight device for a non-self-luminous image display panel
has a light-emitting area corresponding to a display area of the image
display panel. The light-emitting area is arranged by combining a
plurality of backlight substrates each of which is provided with (i) a
color sensor for detecting an incident light intensity and (ii) red,
green, and blue LEDs whose respective light intensities are controlled in
accordance with a detection result obtained by the color sensor. This
arrangement allows reduction of brightness unevenness entirely in the
light-emitting area of the backlight device.

Claims:

1. A backlight device which is a direct type and which is used for a
non-self-luminous image display panel,the backlight device, comprising:a
light-emitting area corresponding to a display area of the image display
panel,the light-emitting area including a plurality of small areas each
of which is provided with (i) a light detecting section for detecting an
intensity of light incident thereon and (ii) one or more light-emitting
sections whose respective light intensities are controlled in accordance
with a detection result obtained by the light detecting section.

2. The backlight device as set forth in claim 1, wherein:the light
detecting section detects respective light intensities of a plurality of
color components; andthe light-emitting sections have the light
intensities that are controlled for a plurality of color components.

3. The backlight device as set forth in claim 1, further comprising a
control section for controlling the respective light intensities of the
light-emitting sections in accordance with the detection result obtained
by the light detecting section.

4. The backlight device as set forth in claim 1, further comprising
substrates each of which includes the light detecting section and the
light-emitting sections thereon and which are divided so as to
respectively correspond to the plurality of small areas.

5. The backlight device as set forth in claim 4, wherein each of the
substrates has a shape similar to a shape of the light-emitting area.

6. The backlight device as set forth in claim 5, wherein the substrate has
dimensions of 81 mm×144 mm.

7. The backlight device as set forth in claim 4, wherein:the plurality of
light-emitting sections are disposed in a matrix manner in each of the
small areas, andthe light detecting section is provided in the small area
so as to be positioned such that: (i) a number of light-emitting sections
disposed in front of the light detecting section in a column direction is
equal to or different by one from a number of light emitting sections
disposed behind the light detecting section in the column direction; and
(ii) a number of light-emitting sections disposed in front of the light
detecting section in a row direction is equal to or different by one from
a number of light emitting sections disposed behind the light detecting
section in the row direction.

8. The backlight device as set forth in claim 4, wherein the substrate has
a surface, including the light-emitting sections thereon, which surface
has been subjected to a reflectance improving process.

9. The backlight device as set forth in claim 1, wherein each of the
light-emitting sections includes three types of light-emitting element
that emit red, green, and blue light, respectively.

10. The backlight device as set forth in claim 9, wherein at least one of
the three types of light-emitting element includes (i) a light source and
(ii) a luminescent material which absorbs light emitted from the light
source and which emits light having a wavelength longer than a wavelength
of the light emitted from the light source.

11. The backlight device as set forth in claim 9, wherein at least one of
the three types of light-emitting element is a semiconductor
light-emitting element formed by using a semiconductor substrate made of
silicon carbide or gallium nitride, and is sealed with a transparent
resin having an index of refraction which lies between an index of
refraction of the semiconductor substrate and an index of refraction of
air.

12. The backlight device as set forth in claim 9, wherein a surface on
which the semiconductor light-emitting element is mounted is plated with
silver.

13. The backlight device as set forth in claim 1, wherein the light
detecting section includes a light-shielding section for preventing light
emitted from the light-emitting sections from being directly incident on
the light detecting section.

14. The backlight device as set forth in claim 4, wherein:each of the
substrates has a temperature detecting section for detecting a
temperature of the substrate, andthe light-emitting sections mounted on
the substrate have the respective light intensities that are further
controlled in accordance with a detection result obtained by the
temperature sensor mounted on the substrate.

15. A display apparatus, comprising:the backlight device as set forth in
claim 1; anda non-self-luminous image display panel for displaying an
image by controlling a transmission state of light emitted from the
backlight device.

16. A backlight device, comprising:a plurality of substrates each of which
includes one or more light-emitting elements, a light sensor, and a
memory; anda driving circuit for driving each of the light-emitting
elements, whereinthe memory of each of the substrates stores information
corresponding to a value of an output produced by the light sensor under
such condition that the light-emitting element emits light having a
predetermined luminance or chromaticity.

17. The backlight device as set forth in claim 16, wherein the substrate
includes the driving circuit for driving the light-emitting element of
the substrate.

18. The backlight device as set forth in claim 16, further comprising a
control circuit for (i) standardizing the output of the light sensor in
accordance with the information stored in the memory corresponding to the
light sensor and (ii) generating a control signal for the driving circuit
so that the standardized output of the light sensor corresponds to a set
value of luminance or chromaticity of the backlight device.

19. The backlight device as set forth in claim 18, wherein the control
circuit is provided outside of the substrate.

20. The backlight device as set forth in claim 19, wherein the control
circuit generates a time-sharing control signal for each of the
substrates.

21. The backlight device as set forth in claim 18, wherein:the control
circuit includes a plurality of control circuits, andeach of the control
circuits is provided in each of the substrates.

22. The backlight device as set forth in claim 16, wherein the
light-emitting elements include a blue light-emitting element, a green
light-emitting element, and a blue light-emitting element.

23. The backlight device as set forth in claim 22, wherein at least one of
the red, green, and blue light-emitting elements includes an LED.

24. The backlight device as set forth in claim 16, wherein the light
sensor is provided on the substrate so as to be disposed substantially in
a central part of a surface having the light-emitting elements.

25. The backlight device as set forth in claim 16, wherein the light
sensor includes (i) a light sensor for detecting blue light, (ii) a light
sensor for detecting green light, and (iii) a sensor for detecting red
light.

26. The backlight device as set forth in claim 16, wherein the
light-emitting element is driven in a time-sharing manner so that the
light sensor detects each of different colors of light emitted from the
light-emitting element.

27. The backlight device as set forth in claim 16, wherein the memory
stores information corresponding to a value of an output produced by the
light sensor under such condition that the light-emitting element
provided in the substrate emits light having a predetermined color
temperature.

28. The backlight device as set forth in claim 22, wherein the memory
stores information corresponding to a value of an output produced by the
light sensor under such condition that each of the red, green, and blue
light-emitting elements provided in the substrate emits light having a
predetermined luminance.

29. The backlight device as set forth in claim 16, wherein the memory
stores information corresponding to variations in luminance or
chromaticity among the light-emitting elements provided in the substrate.

30. The backlight device as set forth in claim 29, wherein the
light-emitting element includes groups of light-emitting elements.

31. The backlight device as set forth in claim 30, further comprising the
light-emitting element in which the groups of light-emitting elements are
serially connected.

32. The backlight device as set forth in claim 19, wherein the memory
stores information corresponding to a condition for driving the
light-emitting elements under such condition that each of the
light-emitting elements emits light having a predetermined luminance or
chromaticity.

33. The backlight device as set forth in claim 19, whereinthe memory
includes:a first memory storing the information corresponding to the
value of the output produced by the light sensor under such condition
that the light-emitting element provided in the substrate emits the light
having the predetermined luminance or chromaticity; anda second memory
storing information corresponding to variations in luminance or
chromaticity among the light-emitting elements provided in the substrate.

34. The backlight device as set forth in claim 16, wherein the substrate
has (i) a surface on which the light-emitting element and the light
sensor are provided and (ii) a rear surface on which the memory is
provided.

35. The backlight device as set forth in claim 16, wherein the memory is
incorporated into an integrated circuit element combined with the driving
circuit.

36. The backlight device as set forth in claim 16, wherein the memory is a
writable or rewritable memory.

37. A display apparatus, comprising:the backlight device as set forth in
claim 16; anda non-self-luminous image display panel for displaying an
image by controlling a transmission state of light emitted from the
backlight device.

38. A method for driving a backlight device including: (i) a plurality of
substrates each of which includes one or more light-emitting elements, a
light sensor, and a memory; (ii) a driving circuit; and (iii) a control
circuit, the memory storing information corresponding to a value of an
output produced by the light sensor under such condition that each of the
light-emitting elements provided in each of the substrates emits light
having a predetermined luminance or chromaticity,the method, comprising
the steps of:causing the driving circuit to drive the light-emitting
element; andcausing the control circuit to (i) standardize the output of
the light sensor in accordance with the information stored in the memory,
(ii) generate such a control signal for the driving circuit that the
standardized output of the light sensor becomes equal to a set luminance
or chromaticity, and (iii) transmit the control signal to the driving
circuit.

39. A method for adjusting a backlight device including a plurality of
substrates each of which includes one or more light-emitting elements, a
light sensor, and a memory,the method, comprising:a first step of (i)
driving each of the light-emitting elements and (ii) detecting, by using
an external light sensor used substantially commonly for the substrates,
a light intensity of the light-emitting element;a second step of
calculating a light sensor output reference value that is expected from
an output produced by the light sensor in the first step; anda third step
of storing the light sensor output reference value in the memory,the
first, second, and third steps being carried out for each of the
substrates.

40. The method as set forth in claim 39, wherein:the light-emitting
elements includes a plurality of different colored light-emitting
elements that emit light of different colors, anda series of steps is
carried out for each of the different colored light-emitting elements
provided in each of the substrates,the series of steps including:a first
step of (i) driving one of the different colored light-emitting elements
and (ii) detecting, by using the external light sensor used substantially
commonly for the substrates, a light intensity of the light-emitting
element;a second step of calculating the light sensor output reference
value that is expected from the output produced by the light sensor in
the first step; anda third step of storing the light sensor output
reference value in the memory.

41. The method as set forth in claim 39, further comprising:a fourth step
of (i) driving the light-emitting element and (ii) detecting, by using
the external light sensor, information corresponding to variations in
luminance or chromaticity among the light-emitting elements provided in
the substrate; anda fifth step of storing, in the memory, the information
corresponding to the variations among the light-emitting elements within
the substrate.

42. The method as set forth in claim 39, wherein the light-emitting
element is a group of light-emitting elements.

43. The method as set forth in claim 41, wherein the first, second, and
third steps are carried out after the fourth and fifth steps are carried
out.

44. The method as set forth in claim 41, whereinthe external light sensor
is an external light sensor for detecting luminance or chromaticity as an
image.

45. The method as set forth in claim 39, whereinat least the third step is
carried out under such condition that a diffusion plate is provided
between the substrate and the external light sensor.

46. The backlight device as set forth in claim 3, further comprising a
reference light intensity data memory storing respective reference light
intensities of the light-emitting sections,wherein the control section
controls the respective light intensities of the light-emitting sections
in accordance with (i) the detection result obtained by the light
detecting section and (ii) the reference light intensities stored in the
reference light intensity data memory.

47. The backlight device as set forth in claim 46, wherein the control
section controls the respective light intensities of the light-emitting
sections so that the respective light intensities of the light-emitting
sections correspond to the reference light intensities stored in the
reference light intensity data memory.

[0002]The present invention relates to (i) a direct-type backlight device
that is used for a non-self-luminous image display panel such as a liquid
crystal display panel and (ii) a liquid crystal display apparatus using
the direct-type backlight device, and is particularly suitable for (a) a
backlight device using an LED as a light source and (b) a liquid crystal
display apparatus using the backlight device.

BACKGROUND OF THE INVENTION

[0003][Background Art of the First Invention]

[0004]Conventionally, an LED backlight in which LEDs (light-emitting
diode) are adopted as a light source has been used as a backlight for a
liquid crystal display apparatus. Controlling luminance and chromaticity
has been an important subject for study, when using an LED backlight.

[0005]The reasons are as follows: LEDs differ from element to element in
their luminescence properties. Particularly, the luminescence properties
differ from production unit to production unit. As such, if LEDs of
different production units are used for a single backlight, then
luminance unevenness and/or color unevenness occur. Furthermore, since
LEDs are semiconductor elements, their luminescence properties such as
luminous efficiency and/or luminescence peak wavelengths also have
changes due to a temperature change and/or a moment-to-moment change, and
the rate of such changes differ from production unit to production unit.
In view of the circumstances, there has been conventionally made an
effort, for example, (i) to use as many LEDs as possible of the same
production unit or (ii) to select and use LEDs having a uniform property.

[0006]There has been conventionally developed a technique for carrying
out, by feeding back signals sent from a color sensor and/or a
temperature sensor that are mounted on an LED backlight, a control such
that the luminance and chromaticity of the backlight become constant
(e.g., see Koichiro Kakinuma, "Wide Color Gamut Reproducing Technique of
LCD Television `LED Backlight for QUALIA 005`", Monthly DISPLAY, July
2005).

[0007]On the other hand, a so-called calibration system, which (i) detects
a color of a display screen image by using a sensor and (ii) adjusts the
color, has been known as a technique for adjusting a color which an image
display apparatus displays (e.g., see Japanese Unexamined Patent
Publication No. 64842/2002 (Tokukai 2002-64842; published on Feb. 28,
2002) and Japanese Unexamined Patent Publication No. 281531/2002 (Tokukai
2002-281531; published on Sep. 27, 2002).

[0008](Background Art of the Second Invention)

[0009]Recently, there has been being developed either (i) a system in
which a combination of a conventionally-used cold cathode fluorescent
light (hereinafter referred to as "CCFL") and light-emitting diodes
(hereinafter referred to as "LEDs") is used as a light source of a
backlight used for a liquid crystal apparatus, or (ii) a system in which
only LEDs are used, instead of CCFLs, as a light source. Particularly, a
system in which the three primary colors red, green, and blue are
obtained by using LEDs alone has a feature of wider color reproducibility
region (NTSC ratio) as compared to a system using a conventional CCFL.
The reason for this is that: each of the LEDs has a narrow half-value
width of emission spectrum, and so almost pure red, green, and blue are
obtained. Furthermore, since it is possible to adjust brightness for each
of the colors in accordance with an electric current, such a system has a
feature of variable color balance. Further, since the LEDs are free of
mercury, the system exhibits excellent environmental friendliness.

[0010]FIGS. 25(a) and 25(b) show an example of a backlight device,
disclosed in U.S. Pat. No. 6,439,731 (issued on Aug. 27, 2002), which
uses LEDs. FIG. 25(a) is a rear view of the device, and FIG. 25(b) is a
front view of the device. LEDs 131 are assembled substantially over the
entire front surface of a printed circuit board 130. Further, the printed
circuit board 130 has a rear surface on which (i) a luminance adjusting
circuit 132 and (ii) a semiconductor chip 133 including a driver and a
control circuit are provided, so that driving of the LEDs 131 is
controlled. On the rear surface of the printed circuit board 130, a heat
sink 134 is provided so that heat due to (a) the LEDs 131, (b) the
luminance adjusting circuit 132, which is provided on the rear surface of
the printed circuit board 130, and (c) the semiconductor chip 133, which
is provided on the rear surface of the printed circuit board 130, is
radiated efficiently. For the purpose of improving thermal conductivity
by bringing the printed circuit board 130 and the heat sink 134 into
close contact with each other, the heat sink 134 is provided with a
concavity 135 so that the luminance adjusting circuit 132 and the
semiconductor chip 133, each of which is provided on the rear surface of
the printed circuit board 130, can be stored in the cavity 135. Further,
provided on the front surface of the printed circuit board 130 is a
diffusion plate 136 for uniforming light emitted from the LEDs 131.
Further, a liquid crystal panel 138 is provided on a front side of an
optical chamber 137 that houses the heat sink 134, the printed circuit
board 130, and the diffusion plate 136. This arrangement realizes, as a
whole, a liquid crystal display apparatus which uses the LEDs 131 as a
backlight.

[0011]Further, WO 02/080625 (published on Oct. 10, 2002) discloses an LED
backlight which includes red, green, and blue LEDs and a set of light
sensors that respectively detect three colors of red, green, and blue,
and in which respective luminances and chromaticities of the LEDs are
stabilized by using the set of light sensors. The LED lighting device
includes a memory array in addition to the LEDs and the light sensors.
The memory array can store respective values of color and lumen output
that have been set by a user. According to the LED lighting device, these
values can be read out from the memory in accordance with the user's
selection.

[0012]Further, WO 00/037904 (published on Jun. 29, 2000) discloses a
backlight device in which respective luminances and chromaticities of
red, green, and blue LEDs are stabilized by driving a single light sensor
in a time-sharing manner.

[0013]Further, Japanese Unexamined Patent Publication No. 286971/2004
(Tokukai 2004-286971; published on Oct. 14, 2004) discloses a backlight
device which uses a light guide plate and in which uniform luminance and
uniform chromaticity can be obtained by using (i) four RGB light sources
that are provided at upper and lower ends of a display area and (ii) four
color sensors that are disposed at left and right ends of the display
area. Here, the four light sources do not meet one-to-one correspondence
with respect to outputs of the four sensors, respectively, and a feedback
control is made by, in order to carry out a matrix operation, comparing
each output of the sensors with data stored in correlation data memory
and light source reference light-emitting amount memory that are common
to the four light sources and the four sensors.

[0014]Further, for the purpose of reducing current consumption and
absorbing variations in characteristics of LEDs, United States Unexamined
Patent Publication No. 2006103612 (published on May 18, 2006) discloses a
device in which applied voltage storage registers store driving voltages
for driving red, green, and blue LEDs, respectively, and in which the
red, green, and blue LEDs are driven by independent driving voltages. The
LED driving device has an R (red) applied voltage storage register, a G
(green) applied voltage storage register, a B (blue) applied voltage
storage register, an R duty ratio storage register, a G duty ratio
storage register, and a B duty ratio storage register. According to this
arrangement and this method, independent minimum driving voltages are
applied to the red, green, and blue LEDs in accordance with the voltage
values stored in applied voltage storing means, respectively. This allows
current consumption to be less as compared with a case where an identical
driving voltage is applied to the red, green, and blue LEDs.

SUMMARY OF THE INVENTION

[0015](Disclosure of the First Invention)

[0016]However, with the technique disclosed in "Wide Color Gamut.
Reproducing Technique of LCD Television `LED Backlight for QUALIA 005`",
it is difficult to sufficiently inhibit luminance unevenness and
chromaticity unevenness from occurring across the screen.

[0017]The reason for this is as follows. According to the technique, since
the color sensor is provided on a side surface of the LED backlight, it
is impossible to individually detect luminance and chromaticity in each
part of a screen, i.e., detect luminance unevenness and chromaticity
unevenness although it is possible to detect luminance and chromaticity
on the entire screen.

[0018]Further, each of the techniques respectively disclosed in the
aforementioned Japanese Unexamined Patent Publications Tokukai 2002-64842
and Tokukai 2002-281531 is a calibrating technique. Therefore, it is
difficult to carry out control for suppressing luminance unevenness and
chromaticity unevenness under the state in which an image display
apparatus is normally used.

[0019]The present invention has been made in view of the foregoing
problems, and it is an object of the present invention to realize a
backlight device in which it is possible to reduce brightness unevenness
and, more preferably, even color unevenness entirely in a light-emitting
area.

[0020]In order to attain the foregoing object, a backlight device
according to the present invention is a backlight device which is a
direct type and which is used for a non-self-luminous image display
panel, the backlight device, including: a light-emitting area
corresponding to a display area of the image display panel, the
light-emitting area including a plurality of small areas each of which is
provided with (i) a light detecting section for detecting an intensity of
light incident thereon and (ii) one or more light-emitting sections whose
respective light intensities are controlled in accordance with a
detection result obtained by the light detecting section.

[0021]With the foregoing arrangement, in each of the plurality of small
areas constituting the light-emitting area, the light detecting section
detects an intensity of light incident on the light detecting section. In
accordance with the detection result obtained by the light detecting
section, the respective light intensities of the light-emitting sections
disposed in the small area are controlled.

[0022]Therefore, with the foregoing arrangement, it is possible to divide
the light-emitting area into the small areas and to adjust the light
intensities for each of the small areas.

[0023]As a result, it becomes possible to make an adjustment so that
brightness unevenness is suppressed for each of the small areas
constituting the light-emitting area. This makes it possible to reduce
brightness unevenness entirely in the light-emitting area.

[0024]A display apparatus according to the present invention is arranged
so as to include: the foregoing backlight device; and a non-self-luminous
image display panel for displaying an image by controlling a transmission
state of light emitted from the backlight device.

[0025]With the foregoing arrangement, it is possible to reduce brightness
unevenness on a display screen.

[0026](Disclosure of the Second Invention)

[0027]Recently, it has been proposed that an LED backlight be applied to a
large liquid crystal display apparatus. In such a case, when a substrate
on which LEDs have been provided is simply enlarged, there occurs such a
problem that brightness (luminance) unevenness or color (chromaticity)
unevenness due to temperature variations in the substrate becomes
prominent. The variations in temperature within the substrate can be
corrected to some extent by an arrangement using a light sensor. However,
it is difficult to overcome luminance unevenness or chromaticity
unevenness entirely. Further, when the substrate is divided, a damaged
part can be repaired easily. In view of this, it is conceivable to
arrange a backlight so as to have a plurality of substrates on which LEDs
have been provided.

[0028]However, in cases where an LED backlight is arranged by using a
plurality of substrates, there is such a problem that it is difficult to
make an adjustment so as to match the chromaticity or luminance of one
substrate to the chromaticity and luminance of another substrate. When
the adjustment is insufficient and such a backlight device is used as a
backlight, especially, for a liquid crystal display, there occurs
variations in luminance or chromaticity in a display area of the liquid
crystal display. Further, for this reason, in cases where one of the
substrates is damaged and therefore is repaired or replaced, it takes a
lot of trouble to make an adjustment so that the repaired or replacing
substrate emits light identical to light emitted from neighboring
substrates.

[0029]It is an object of the present invention to provide (i) a backlight
device in which each substrate is automatically adjusted so as to have a
predetermined luminance or chromaticity and which emits light uniformly,
(ii) a display apparatus using the backlight device, and (iii) a method
for driving the backlight device.

[0030]Further, it is an object of the present invention to provide a
method for adjusting substrates constituting such a backlight device.

[0031]The present invention is a backlight device, including: a plurality
of substrates each of which includes one or more light-emitting elements,
a light sensor, and a memory; and a driving circuit for driving each of
the light-emitting elements, wherein the memory of each of the substrates
stores information corresponding to a value of an output produced by the
light sensor under such condition that the light-emitting element emits
light having a predetermined luminance or chromaticity.

[0032]According to the present invention, in the backlight device
including the plurality of substrates, the memory of each of the
substrates stores, in advance, information corresponding to a value of an
output produced by the light sensor under such condition that the
light-emitting element provided in the substrate emits light having a
predetermined luminance or chromaticity. By using this information, the
value of the output of the light sensor is standardized. Feedback control
of the light-emitting element provided in the substrate is carried out
such that the standardized value of the output of the light sensor
corresponds to a set value of luminance or chromaticity. With this, an
automatic adjustment is carried out such that a predetermined value of
luminance or chromaticity is obtained for the substrate. Therefore, since
the substrate is not affected by variations in the light sensor, a
backlight device that emits light uniformly can be obtained simply by
combining the substrates unadjusted. Accordingly, simply by replacing a
damaged substrate with a substrate having a memory storing such
information, it is possible to arrange a backlight device in which a
plurality of substrates emit light of uniform luminance or chromaticity
even after one of the substrates has been replaced by another substrate.

[0033]The present invention is a display apparatus, including: the
foregoing backlight device; and a non-self-luminous image display panel
for displaying an image by controlling a transmission state of light
emitted from the backlight device.

[0034]Further, according to the present invention, it is possible to
provide, by combining (i) the backlight device having excellent
uniformity with (ii) the non-self-luminous image display panel, a display
apparatus having excellent display quality.

[0035]The present invention is a method for driving a backlight device
including: (i) a plurality of substrates each of which includes one or
more light-emitting elements, a light sensor, and a memory; (ii) a
driving circuit; and (iii) a control circuit, the memory storing
information corresponding to a value of an output produced by the light
sensor under such condition that each of the light-emitting elements
provided in each of the substrates emits light having a predetermined
luminance or chromaticity, the method, including the steps of: causing
the driving circuit to drive the light-emitting element; and causing the
control circuit to (i) standardize the output of the light sensor in
accordance with the information stored in the memory, (ii) generate such
a control signal for the driving circuit that the standardized output of
the light sensor becomes equal to a set luminance or chromaticity, and
(iii) transmit the control signal to the driving circuit.

[0036]Further, according to the present invention, it is possible to
provide a method for driving the backlight device having excellent
uniformity.

[0037]The present invention is a method for adjusting a backlight device
including a plurality of substrates each of which includes one or more
light-emitting elements, a light sensor, and a memory, the method,
including: a first step of (i) driving each of the light-emitting
elements and (ii) detecting, by using an external light sensor used
substantially commonly for the substrates, a light intensity of the
light-emitting element; a second step of calculating a light sensor
output reference value that is expected from an output produced by the
light sensor in the first step; and a third step of storing the light
sensor output reference value in the memory, the first, second, and third
steps being carried out for each of the substrates.

[0038]Further, according to the present invention, it is possible to
provide a method for adjusting a substrate that can be incorporated
directly into the backlight device.

[0039]Additional objects, features, and strengths of the present invention
will be made clear by the description below. Further, the advantages of
the present invention will be evident from the following explanation in
reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0040]FIG. 1(a) is a plan view showing a liquid crystal display apparatus
of Embodiment 1 of the First Invention, and FIG. 1(b) is a side view
showing the liquid crystal display apparatus.

[0041]FIG. 2(a) is a plan view showing a backlight and an internal frame
each provided in the liquid crystal display apparatus, and FIG. 2(b) is a
side view showing the backlight, the internal frame, and a backlight
control circuit each provided in the liquid crystal display apparatus.

[0042]FIG. 3 is a plan view showing an arrangement of a backlight unit
provided in the liquid crystal display apparatus.

[0043]FIG. 4 is a perspective view showing the backlight unit mounted on
the internal frame of the liquid crystal display apparatus.

[0044]FIG. 5 is a plan view showing a configuration of backlight
substrates each constituting the backlight unit.

[0045]FIG. 6 is a diagram for explaining that backlights having
light-emitting areas of various sizes can be arranged by combining the
backlight substrates.

[0046]FIG. 7 is a chart showing a relationship between (i) a screen size
and (ii) the number of backlight substrates for constituting the screen
size.

[0047]FIG. 8 is a plan view for explaining the location of a color sensor
in each of the backlight substrates.

[0048]FIG. 9 is a cross-sectional view showing a liquid crystal unit, the
backlight, the internal frame, and the backlight control circuit each
provided in the liquid crystal display apparatus.

[0049]FIG. 10 is a plan view showing red, green, and blue LEDs sealed with
a resin.

[0050]FIG. 11 is a plan view showing an example of the configuration of
red, green, and blue LEDs.

[0051]FIG. 12 is a plan view showing an arrangement of a backlight unit
provided in a liquid crystal display apparatus of Embodiment 2 of the
First Invention.

[0052]FIG. 13 is a diagram schematically showing a rear surface of a
liquid crystal display apparatus of Embodiment 1 of the Second Invention.

[0053]FIGS. 14(a) and 14(b) are diagrams schematically showing a tile
provided in a backlight device of Embodiment 1 of the Second Invention.

[0054]FIG. 15 is a cross-sectional view of the tile provided in the
backlight device of Embodiment 1 of the Second Invention.

[0055]FIG. 16 is an enlarged sectional view of the tile provided in the
backlight device of Embodiment 1 of the Second Invention.

[0056]FIGS. 17(a) and 17(b) are diagrams schematically showing a flow of
signals of Embodiment 1 of the Second Invention.

[0057]FIG. 18 shows a device for adjusting a tile that is to be provided
in the backlight device of Embodiment 1 of the Second Invention.

[0058]FIGS. 19(a) and 19(b) are front and rear views of a tile provided in
a backlight device of Embodiment 2 of the Second Invention, respectively.

[0059]FIG. 20 shows a device for adjusting a tile that is to be provided
in the backlight device of Embodiment 2 of the Second Invention.

[0060]FIG. 21 is a cross-sectional view of a tile provided in a backlight
device of Embodiment 3 of the Second Invention.

[0061]FIG. 22 is an enlarged sectional view of the tile provided in the
backlight device of Embodiment 3 of the Second Invention.

[0062]FIG. 23 is a diagram schematically showing a surface of the tile
provided in the backlight device of Embodiment 3 of the Second Invention.

[0063]FIG. 24 shows a device for adjusting a tile that is to be provided
in the backlight device of Embodiment 3 of the Second Invention.

[0064]FIGS. 25(a) and 25(b) show a liquid crystal display apparatus using
a conventional backlight device.

DESCRIPTION OF THE EMBODIMENTS

Embodiment 1 of the First Invention

[0065]Embodiment 1 of the present invention will be described below with
reference to FIGS. 1 through 11.

[0066]First, an arrangement of a liquid crystal display apparatus (display
apparatus) 1 according to the present embodiment will be schematically
described with reference to FIGS. 1(a) and 1(b). The liquid crystal
display apparatus 1 includes a liquid crystal unit 2, a backlight 3, an
internal frame 4, a backlight control section (control section) 5, and a
driving and power supply circuit 6, which are disposed in this order from
a front side of the liquid crystal display apparatus 1 toward a rear side
of the liquid crystal display apparatus 1.

[0067]Among these components of the liquid crystal display apparatus 1,
the liquid crystal unit 2 and the driving and power supply circuit 6 are
conventional ones.

[0068]That is, the liquid crystal unit 2 includes a pair of substrates
between which sandwich a liquid crystal material is sandwiched and on
which a color filter, a polarizing film, and other members are provided.
Further, the driving and power supply circuit 6 carries out driving and
control of the entire liquid crystal display apparatus 1 by supplying the
liquid crystal unit 2, the backlight control section 5, and other members
with (i) power for operating and (ii) signals for them.

[0069]In the following, the backlight 3 and the backlight control section
5 each according to the present embodiment will be described.

[0070]The backlight 3 is designed to supply white light to the liquid
crystal unit 2, which is a non-self-luminous image display panel. The
backlight 3 is arranged so that a large number of light-emitting elements
are mounted on a substrate.

[0071]As will be described later, the backlight 3 of the present
embodiment is arranged by combining a plurality of substrates each having
light-emitting elements mounted thereon. A light-emitting element to be
mounted on each of the substrates is adjusted in advance so as to have a
predetermined luminance and a predetermined chromaticity.

[0072]However, when the substrates are combined and the light-emitting
elements mounted on each of the substrates are turned on while the
substrates have been set to the same setting, luminance unevenness and
color unevenness occur in a display area of the liquid crystal unit 2.
The simple reason for this is that an area of substrates disposed in a
central portion of the liquid crystal unit 2 and an area of substrates
disposed in a peripheral portion of the liquid crystal unit 2 are
different from each other in terms of ambient incoming light conditions,
temperature conditions, and the like.

[0073]In view of this, according to the backlight 3 of the present
embodiment, luminance and chromaticity are measured for each of the
substrates by using a sensor, and an automatic adjustment is carried out
so that a predetermined luminance and a predetermined chromaticity are
obtained. With this, luminance unevenness and color unevenness are
suppressed in the entire display area of the liquid crystal unit 2, so
that luminance and chromaticity are uniform.

[0074]Further, the continuing use of the backlight 3 causes (i) a change
in temperature distribution in the display area of the liquid crystal
unit 2, (ii) a change in ambient temperature in the display area of the
liquid crystal unit 2, (iii) a moment-to-moment change in respective
luminescence intensities of the light-emitting elements, (iv) variations
in the moment-to-moment change among the light-emitting elements, and (v)
the like. This causes the entire display area to lose uniformity in
luminance and chromaticity.

[0075]In view of this, according to the backlight 3 of the present
embodiment, even while the liquid crystal display apparatus 1 is being
used, the adjustment using the sensor is carried out so that a
predetermined luminance and a predetermined chromaticity are obtained.
With this, luminance unevenness and color unevenness are suppressed.

[0076]For that purpose, the backlight 3 and the backlight control section
5 each according to the present embodiment are arranged as described
below.

[0077]As shown in FIGS. 2(a) and 2(b), the backlight 3 of the present
embodiment is not made up of a single substrate, but is made up of a
large number of backlight substrates 31 each of which has a size
corresponding to a size of each of portions obtained by equally dividing
the display area of the liquid crystal unit 2 in a matrix manner. The
backlight substrates 31 are fixed onto a front-side surface of the
internal frame 4 so as to be disposed in a matrix manner.

[0078]Further, the backlight control section 5 controls the light-emitting
elements of the backlight 3. The backlight control section 5 includes: a
large number of control substrates 51 provided so as to respectively
correspond to the backlight substrates 31; and control circuits
respectively mounted on the control substrates 51.

[0079]The following description assumes such an arrangement that the
backlight substrates 31 and the control substrates 51 meet one-to-one
correspondence with respect to each other. In this case, the backlight
substrates 31 and the control substrates 51 that correspond to each other
are connected, for example, by flexible wires through openings (not
shown) formed in the internal frame 4, respectively. With such an
arrangement, it becomes easy to understand correspondence between the
backlight substrates 31 and the control substrates 51, and each of the
wires respectively connecting the backlight substrates 31 to the control
substrates 51 has a short length. This brings about such an advantage
that: the influence of noise is limited, so that a signal has a good S/N
ratio.

[0080]However, when it becomes necessary to dispose another circuit or the
like on a rear-side surface of the internal frame 4, the foregoing
arrangement may be hardly realized.

[0081]The control substrates 51 can be disposed in many variations, and it
is possible to arrange a backlight control section 5 that is not divided
into a large number of control substrates 51.

[0082]The backlight 3 and the backlight control section 5 constitute a
direct-type backlight device 7 according to the present invention. The
direct-type backlight device 7 includes an arrangement in which there are
provided (i) a pair of a backlight substrate 31 and a control substrate
51 that correspond to each other as described above and (ii) circuit
elements respectively mounted on the backlight substrate 31 and the
control substrate 51. Such an arrangement is referred to as "backlight
units 71" (see FIG. 3).

[0083]Note that a direct-type backlight device refers to such an
arrangement that a plurality of light sources are arranged directly below
a back side of a display area of a non-self-luminous image display panel
such as a liquid crystal unit 2.

[0084]The arrangement of the backlight unit 71 will be fully described
with reference to FIG. 3. FIG. 3 illustrates the backlight substrate 31
and the control substrate 51 that are arranged in a plane. However, as
shown in FIG. 4, the backlight substrate 31 and the control substrate 51
are mounted on the internal frame 4 so as to sandwich the internal frame
4.

[0085]The backlight substrate 31 includes, as light-emitting elements, a
plurality of red LEDs, a plurality of green LEDs, and a plurality of blue
LEDs. Note that: in FIG. 3, each of the red LEDs, each of the green LEDs,
and each of the blue LEDs are represented by "R", "G", and "B",
respectively. The red, green, and blue LEDs are independently wired, and
therefore are independently driven. That is, respective light intensities
of the red, green, and blue LEDs can be adjusted individually.

[0086]Further, the backlight substrate 31 has a color sensor (light
detecting section) 31a mounted near the center of the backlight substrate
31. The color sensor 31a detects respective light intensities of red,
green, and blue components of light reaching the location of the color
sensor 31a, and outputs a three-channel signal indicating the respective
light intensities of the red, green, and blue components.

[0087]According to the foregoing arrangement, an area, corresponding to
the backlight substrate 31, in the display area of the liquid crystal
unit 2 is illuminated mainly by light emitted from the red, green, and
blue LEDs mounted on the backlight substrate 31, and the color sensor 31a
mounted on the backlight substrate 31 detects respective light
intensities of red, green, and blue components of average light that
illuminates the area.

[0088]Meanwhile, the control substrate 51 controls the respective light
intensities of the red, green, and blue LEDs of the corresponding
backlight substrate 31 in accordance with the light intensities of the
red, green, and blue components, which light intensities have been
detected by the color sensor 31a of the corresponding backlight substrate
31.

[0089]For that purpose, the control substrate 51 includes an A/D
converting section 51a, a light intensity calculating section 51b, a
control amount calculating section 51c, a correlation data memory 51d, a
reference light intensity data memory 51e, and an LED driving section
51f. The following explains a control operation carried out by the
components.

[0090]The three-channel analog signal (the signal indicating the
respective light intensities of the red, green, and blue components) sent
from the color sensor 31a is converted into a digital signal by the A/D
converting section 51a, and the digital signal is sent to the light
intensity calculating section 51b.

[0091]The light intensity calculating section 51b specifies, in accordance
with the digital signal that is sent from the A/D converting section 51a
and with reference to correlation data stored in the correlation data
memory 51d, light intensities (predicted light intensities) which the
red, green, blue LEDs are respectively predicted to have. The light
intensity calculating section 51b outputs a signal indicative of the
predicted light intensities to the control amount calculating section
51c.

[0092]Note that the correlation data stored in the correlation data memory
51d is data which takes the form of a look-up table and which indicates
an experimentally pre-calculated correlation between (i) the respective
light intensities of the red, green, and blue components, which light
intensities are detected by the color sensor 31a, and (ii) the respective
predicted light intensities of the red, green, and blue LEDs.

[0093]The control amount calculating section 51c makes a comparison
between (i) the respective predicted light intensities of the red, green,
and blue LEDs as specified by the light intensity calculating section 51b
and (ii) reference light intensity data stored in the reference light
intensity data memory 51e. The control amount calculating section 51c
calculates a control amount for matching the respective light intensities
of the red, green, and blue LEDs to the reference light intensities. The
control amount calculating section 51c outputs a signal indicative of the
control amount to the LED driving section 51f.

[0094]Note that the reference light intensity data stored in the reference
light intensity data memory 51e is data which indicates reference values
for the respective light intensities of the red, green, blue LEDs.

[0095]The LED driving section 51f generates, in accordance with the signal
sent from the control amount calculating section 51c, a driving signal
for driving the red, green, and blue LEDs, and supplies the driving
signal to the red, green, and blue LEDs. The driving signal may be a
current signal that causes the light intensities to be changed depending
on a current value, or may be a PWM signal that causes the light
intensities to be changed depending on a pulse width.

[0096]The backlight control section 5 is connected to the driving and
power supply section 6. The driving and power supply section 6 supplies
power to the backlight control section 5, and carries out overall control
(control common to all the control substrates 51, e.g., changing of the
light intensity of the entire screen) of the backlight control section 5.

[0097]Backlight units 71 as described above are disposed in a matrix
manner as shown in FIG. 5, so that a light-emitting area that corresponds
to the display area of the liquid crystal unit 2 is realized.

[0098]The backlight substrate 31 has a height of 81 mm and has a width of
144 mm. A total of 49 backlight substrates 31, i.e., 7×7 backlight
substrates 31 (7 backlight substrates 31 wide by 7 backlight substrates
31 high) are disposed, so that a light-emitting area that corresponds to
a 46-inch display area having a height of 573 mm and a width of 1018 mm
is realized. Further, each of the backlight substrates 31 includes: (i) a
total of 28 sets of red, green, and blue LEDs, i.e., 7×4 sets of
red, green, and blue LEDs (In FIG. 4, for the purpose of simplicity, the
number of sets of red, green, and blue LEDs is less than 28); and (ii) a
color sensor 31a. These concrete figures serve as an example, and can be
changed in various ways.

[0099]As described above, the backlight 3 has a light-emitting area that
corresponds to the display area of the liquid crystal unit 2. (In FIG. 5,
the light-emitting area corresponds to the area in which the 7×7
backlight substrates 31 are bedded.) The light-emitting area is made up
of a plurality of small areas. (In FIG. 5, the small areas respectively
correspond to the backlight substrates 31.) Disposed in each of the small
areas are (i) a color sensor 31a and (ii) sets of red, green, and blue
LEDs whose respective light intensities are controlled in accordance with
a detection result obtained by the color sensor 31a.

[0100]With this, the color sensor 31a detects a light intensity in each of
the small areas, and the respective light intensities of the red, green,
and blue LEDs can be controlled in accordance with the detection result.

[0101]This control is carried out such that, as described above, the
respective light intensities of the red, green, and blue LEDs correspond
to the reference light intensity data stored in the reference light
intensity data memory 51e. Therefore, when the same reference light
intensity data is used for each of the backlight substrates 31, the small
area has such a brightness that the entire light-emitting area has a
substantially uniform brightness. That is, it becomes possible to carry
out such an adjustment as to suppress uneven brightness in each of the
small areas of the light-emitting area. This makes it possible to reduce
uneven brightness in the entire light-emitting area.

[0102]Further, the color sensor 31a detects the respective light
intensities of the red, green, and blue components of the light reaching
the location of the color sensor 31a, and the red, green, and blue LEDs
are controlled so that the respective light intensities of the red,
green, and blue LEDs correspond to the reference light intensities. This
makes it possible to adjust, to a color determined by the respective
reference light intensities of the red, green, and blue LEDs, a color
obtained by mixing respective colors of the red, green, and blue LEDs.
This makes it possible to reduce color unevenness as well as uneven
brightness.

[0103]The arrangement may be such that only uneven brightness is reduced.
In such a case, it is not necessary to detect the respective light
intensities of the red, green, and blue components, the color sensor 31a
may be replaced by a sensor capable of detecting a whole intensity of
visible light.

[0104]Further, the light-emitting area only needs to include a plurality
of small areas each of which is provided with (i) a color sensor 31a and
(ii) red, green, and blue LEDs whose respective light intensities are
controlled in accordance with a detection result obtained by the color
sensor 31a. Therefore, the light-emitting area does not need to be
divided into substrates that respectively correspond to the small areas.
However, by dividing the light-emitting area into the substrates that
respectively correspond to the small areas, it becomes possible that: as
shown in FIG. 6, backlights having light-emitting area of various sizes
are easily arranged by combining identically arranged substrates
(backlight substrates 31).

[0105]Each of the backlight substrates 31 preferably has a shape similar
to a shape of the light-emitting area. The light-emitting area
corresponds to a display area of an image display panel, and the display
area generally has a rectangular shape having a predetermined aspect
ratio. Therefore, when the backlight substrate 31 has a shape similar to
a shape of the display area, it becomes easy to arrange backlights having
light-emitting areas corresponding to display areas of various sizes.

[0106]Further, the backlight substrate 31 preferably has a height of 81 mm
and a width of 144 mm. This size makes it possible that: as shown in FIG.
7, backlights having light-emitting area substantially corresponding in
size to display areas of typical sizes (13, 15, 20, 26, 32, 37, 40, 42,
45, 46, 52, 57, 58, 59, and 65 inches) are arranged by disposing an
integral number of backlight substrates 31 longitudinally and
transversely.

[0107]Each of the backlight substrates 31 may have a width half the
aforementioned width, i.e., may have a height of 81 mm and a width of 72
mm. Alternatively, the backlight substrate 31 may have a height double
the aforementioned height, i.e., may have a substantially square shape
having a height of 162 mm and a width of 144 mm. Further, the backlight
substrate 31 may have a height of 81 mm and a width of 48 mm. The
backlight substrate 31 may have other various sizes.

[0108]Further, the foregoing description assumes that the backlight
substrates 31 are disposed so as to leave no space therebetween. However,
the backlight substrates 31 do not necessarily need to be disposed in
such a manner. Alternatively, it is possible that the backlight
substrates 31 are disposed so as to have such a space therebetween that
no color unevenness occurs.

[0109]The color sensor 31a preferably detects an average light condition
in each of the small areas. For that purpose, the color sensor 31a is
preferably disposed in substantially the middle of the red, green, and
blue LEDs mounted on each of the backlight substrates 31. Specifically,
as shown in FIG. 8, the color sensor 31a is preferably provided in
substantially the center of the backlight substrate 31 (i.e., in the
position indicated by "+" in FIG. 8). This is realized by an arrangement
in which sets of red, green, and blue LEDs (each of which sets is circled
by a dotted line in FIG. 8) are disposed in a matrix manner so that: (i)
the same number of sets of red, green, and blue LEDs are disposed in
front of and behind the color sensor 31a in column and row directions,
respectively. In cases where an odd number of sets of red, green, and
blue LEDs are disposed in a column direction or in a row direction, the
difference may be 1 between the numbers of sets of red, green, and blue
LEDs disposed in front of and behind the color sensor 31a.

[0110]In the following, the backlight substrate 31 and a circuit element
mounted thereon will be fully described with reference to FIG. 9. Note
that FIG. 9 is a cross-sectional view of the liquid crystal unit 2, the
backlight 3, the internal frame 4, and the backlight control section 5.
Further, in the following, the red, green, and blue LEDs is collectively
called "LED 31b" in cases where the colors respectively produced by the
red, green, and blue LEDs are not particularly distinguished.

[0111]According to the arrangement shown in FIG. 9, for the purpose of
minimizing an increase in temperature of the LED 31b (light-emitting
section, light-emitting element, semiconductor light-emitting element),
heat due to the LED 31b is efficiently diffused. Specifically, the
backlight substrate 31 includes (i) a base material 31c made of a highly
thermally conductive material such as aluminum, (ii) a thin (e.g., 60
μm to 80 μm) insulating layer 31d which is formed on a surface of
the base material 31c and which is made of a resin and the like, and
(iii) a wiring pattern 31e made of a highly thermally and electrically
conductive material such as copper, the insulating layer 31d being
interposed between the base material 31c and the wiring pattern 31e.
Moreover, the LED 31b that is a single-wire type is mounted on the wiring
pattern 31e. Furthermore, the backlight substrate 31 is provided so that
a rear surface of the base material 31c has contact with the internal
frame 4 made of a highly thermally conductive material such as aluminum
or stainless steel.

[0112]The single-wire-type LED 31b includes a semiconductor substrate
whose bottom surface serves as one electrode of the LED 31b. Therefore,
the LED 31b can be electrically connected by bringing the bottom surface
into direct contact with the wiring pattern 31e, so that only the other
electrode formed on a surface opposite to the bottom surface of the
semiconductor substrate is connected to the wiring pattern 31e by a wire
31f.

[0113]According to the foregoing arrangement, the heat due to the LED 31b
can be efficiently diffused, through the highly thermally conductive
wiring pattern 31e, the thin insulating layer 31d, and the highly
thermally conductive base material 31c, into the internal frame 4 having
high heat capacity.

[0114]Further, according to the arrangement shown in FIG. 9, the
semiconductor substrate of the semiconductor light-emitting element
constituting the LED 31b is made of silicon carbide (SiC), gallium
nitride (GaN), or the like, and the LED 31b is sealed with a transparent
resin. In case where the semiconductor substrate is made of SiC or GaN,
the semiconductor substrate has a high refractive index of 3.09 (SiC) or
2.48 (GaN), although the figure may vary depending on measurement
conditions. Therefore, there is a big difference in refractive index
between the semiconductor substrate and the air, so that little light
travels through the semiconductor substrate so as to be sent out. For
this reason, in cases where the semiconductor substrate is a SiC or GaN
substrate, the LED 31b is preferably sealed with a transparent resin 31g
having a refractive index that lies between the refractive index of the
semiconductor substrate and the refractive index of the air. (The
transparent resin 31g may have a color as long as it allows transmission
of light. Most transparent resins correspond to the transparent resin
31g.)

[0115]According to this arrangement, the transparent resin 31g is provided
on a path of light which is emitted from a light-emitting layer of the
semiconductor light-emitting element and which travels through the
semiconductor substrate so as to be sent out. This allows a gradual
change in refractive index on the path leading from the semiconductor
substrate to the outside (air). This makes it possible to take out more
light from the path, so that the light can be used more efficiently.

[0116]Further, when the LED 31b is sealed with the transparent resin 31g,
the LED 31b can be protected from accidental mechanical contact during
assembly and inspection regardless of the refractive index of the
semiconductor substrate.

[0117]The LED 31b may be sealed one by one with the transparent resin 31g.
However, as shown in FIG. 10, one or more sets of red, green, and blue
LEDs may be sealed together. However, when too many sets of red, green,
and blue LEDs are sealed together, a large portion of the backlight
substrate 31 is covered with the transparent resin 31g. In this case, the
transparent resin 31g may peel from the backlight substrate 31 because of
a difference in expansion rate between the backlight substrate 31 and the
transparent resin 31g. Therefore, it is preferable that a set of red,
green, and blue LEDs be sealed together.

[0118]Further, according to the arrangement shown in FIG. 9, a surface on
which the LED 31b is mounted is covered with silver plating 31h.

[0119]According to this arrangement, the light which is emitted from the
light-emitting layer of the semiconductor light-emitting element and
which travels through the semiconductor substrate so as to be sent out to
the surface on which the semiconductor light-emitting element is mounted
can be efficiently reflected by the silver plating 31h. Therefore, the
light which is sent out to the surface on which the semiconductor
light-emitting element is mounted becomes able to be taken out
efficiently, so that the light can be used more efficiently.

[0120]See a case where the semiconductor light-emitting element has a
substrate which is a crystal substrate made of sapphire or the like. Also
in such a case, when the surface on which the semiconductor
light-emitting element is mounted is covered with the silver plating 31h,
it is possible to efficiently reflect, with the use of the silver plating
31h, the light which is emitted from the light-emitting layer of the
semiconductor light-emitting element and which travels through the
crystal substrate so as to be sent out to the surface on which the
semiconductor light-emitting element is mounted. Therefore, the provision
of the silver plating 31h is effective also in cases where the
semiconductor light-emitting element has a substrate which is a crystal
substrate made of sapphire or the like.

[0121]Further, the silver plating 31h is also preferably covered with the
transparent resin 31g. With this, oxidization of the silver plating 31h
can be prevented, and the silver plating 31h can retain its high
reflectance for a long period of time. For the purpose of preventing
oxidization, the silver plating 31h may be made of silver alloy instead
of pure silver.

[0122]Furthermore, the backlight substrate 31 preferably has a surface
subjected to a reflectance improving process. The reflectance improving
process refers to a process of improving a light reflectance of the
surface of the backlight substrate 31, and is realized, for example, by
(i) applying a white resin onto the surface of the backlight substrate 31
or (ii) pasting a high-reflectance sheet to the surface of the backlight
substrate 31. For the purpose of not inhibiting the LED 31b and the color
sensor 31a from being electrically connected to the wring pattern 31e
formed on the backlight substrate 31, the application of the white resin
or the pasting of the high-reflectance sheet is carried out so that
respective mounting positions of the LED 31b and the color sensor 31a are
exposed. Since the backlight substrate 31 becomes hot, it is preferable
that a heat-resistant white resin be used in cases where the application
of the white resin is carried out.

[0123]According to this arrangement, the intensity of light that is to be
lost in the backlight substrate 31 is reduced. This makes it possible
that the light emitted from the LED 31b is used more efficiently.

[0124]Further, according to the arrangement shown in FIG. 9, the color
sensor 31a includes a light-shielding section 31i for preventing the
light emitted from the LED 31b from being directly incident on the color
sensor 31a.

[0125]According to this arrangement, the light emitted from the LED 31b
falls indirectly on the color sensor 31a (e.g., light diffused, for
example, by the liquid crystal unit 2, especially a diffusion plate 2a
provided in the liquid crystal unit 2, falls on the color sensor 31a), it
becomes possible to detect light similar to light observed via the liquid
crystal unit 2.

[0126]According to the present embodiment, the red, green, and blue LEDs
are used as the light-emitting elements that are to be mounted on the
backlight substrate 31. However, part or all of the light-emitting
elements may be replaced by a light-emitting element that emits light of
a predetermined color by using a combination of (i) a light source such
as an LED and (ii) a luminescent material which absorbs light emitted
from the light source and which emits light having a wavelength longer
than that of the light emitted from the light source.

[0127]Further, concrete examples of the light-emitting elements that are
to be mounted on the backlight substrate 31 are as follows. Examples of
the green and blue light-emitting elements include: (i) a GaN
light-emitting element mounted on a sapphire substrate; (ii) a GaN
light-emitting element mounted on a SiC substrate; and (iii) an element
obtained by pasting, to another member (e.g., Si), a GaN light-emitting
layer which has grown on a SiC substrate and which has been peeled away
from the SiC substrate. Examples of the red light-emitting element
include: (a) an AlGaInP light-emitting element mounted on a GaAs
substrate; and (b) an element obtained by pasting, to another member
(e.g., Si), an AlGaInP light-emitting layer which has grown on a GaAs
substrate and which has been peeled away from the GaAs substrate.

[0128]Further, the red, green, and blue LEDs may be disposed on the
backlight substrate 31 in various ways. For example, as shown in FIG. 3,
sets of red, green, and blue LEDs are disposed. For example, as shown in
FIG. 11, lines of red LEDs, lines of green LEDs, and lines of blue LEDs
are disposed.

Embodiment 2 of the First Invention

[0129]Embodiment 2 of the present invention will be described below with
reference to FIG. 12.

[0130]The main differences between the present embodiment and Embodiment 1
described above are as follows: (1) the present embodiment has a
temperature sensor 31a added to the backlight substrate 31; (2) the
present embodiment has a temperature characteristic data memory 51g added
to the control substrate 51; and (3) the functional blocks provided on
the control substrate 51 carry out control in accordance with (i) a
detection result obtained by the color sensor 31a and (ii) a detection
result obtained by the temperature sensor 31j.

[0131]Therefore, the following description centers on the differences
described above. Note that components having the same functions as those
corresponding to the components of Embodiment 1 are given the same
reference numerals.

[0132]The backlight substrate 31 has the temperature sensor 31j mounted
thereon. The temperature sensor 31j detects a temperature of a position,
where the temperature sensor 31j is mounted, of the backlight substrate
31, and outputs a signal indicating the detected temperature.

[0133]The analog signal (the signal indicating the detected temperature)
sent from the temperature sensor 31j is converted into a digital signal
by the A/D converting section 51a. The digital signal is sent to the
control amount calculating section 51c.

[0134]First, the control amount calculating section 51c calculates a
control amount corresponding to the detected temperature. The calculation
is carried out in accordance with (i) the temperature detected by the
temperature sensor 31j, (ii) temperature characteristic data concerning
the red, green, and blue LEDs and stored in the temperature
characteristic data memory 51g. Then, the control amount calculating
section 51c outputs a signal indicative of the control amount to the LED
driving section 51f.

[0135]Note that the temperature characteristic data stored in the
temperature characteristic data memory 51g is data which indicates
control amounts correlated to various detected temperatures. Respective
luminescence properties of the red, green, and blue LEDs change in
accordance with respective temperatures of the red, green, and blue LEDs,
and the respective luminescence properties of the red, green, and blue
LEDs changes to various degrees. In view of this, control amounts
(current values in cases where driving is carried out using current
signals; pulse widths in cases where driving is carried out using PWM
signals) serving as references for the red, green, and blue LEDs are
pre-calculated with respect to various temperatures, and are stored as
the temperature characteristic data in the temperature characteristic
data memory 51g. By carrying out control, as described above, with the
use of the temperature characteristic data, the red, green, and blue LEDs
can be set to respectively have approximate desired light intensities.

[0136]Then, as is the case for Embodiment 1, the control amount
calculating section 51c makes a comparison between (i) the respective
predicted light intensities of the red, green, and blue LEDs as specified
by the light intensity calculating section 51b and (ii) the reference
light intensity data stored in the reference light intensity data memory
51e. The control amount calculating section 51c calculates a control
amount for matching the respective light intensities of the red, green,
and blue LEDs to the reference light intensities. The control amount
calculating section 51c outputs a signal indicative of the control amount
to the LED driving section 51f. This makes it possible to more accurately
control the respective light intensities of the red, green, and blue
LEDs.

[0137]As described above, in the present embodiment, the backlight
substrate 31 includes the temperature sensor 31j for detecting a
temperature of the substrate. Furthermore, the respective light
intensities of the red, green, and blue LEDs mounted on the backlight
substrate 31 are controlled in accordance with the detection result
obtained by the temperature 31j mounted on the substrate.

[0138]This arrangement makes it possible to control the respective light
intensities of the red, green, and blue LEDs in consideration of the fact
that respective light-emitting states of the red, green, and blue LEDs
change due to a change in the temperature of the backlight substrate 31.

[0139]The backlight substrate 31 may include a nonvolatile memory (e.g., a
ROM) storing respective characteristics of the red, green, and blue LEDs
mounted on the substrate. The red, green, and blue LEDs have light
intensities that decrease as the temperature increases, and produce
colors (i.e., have luminescence wavelengths) that change as the
temperature increases. The light intensity and color of one of the red,
green, and blue LEDs change differently from those of another one of the
red, green, and blue LEDs. (This is attributed, for example, to (i)
variations between manufactures, (ii) variations between lots, and (iii)
variations within a lot.) In view of this, information concerning such
differences in characteristic (a) is acquired by carrying out preliminary
inspection, (b) is stored in the nonvolatile memory, and (c) is referred
to when the aforementioned control is carried out. This makes it possible
to carry out control more accurately.

[0140]As described above, a backlight device according to the present
invention is a backlight device which is a direct type and which is used
for a non-self-luminous image display panel, the backlight device,
including: a light-emitting area corresponding to a display area of the
image display panel, the light-emitting area including a plurality of
small areas each of which is provided with (i) a light detecting section
for detecting an intensity of light incident thereon and (ii) one or more
light-emitting sections whose respective light intensities are controlled
in accordance with a detection result obtained by the light detecting
section.

[0141]With the foregoing arrangement, in each of the plurality of small
areas constituting the light-emitting area, the light detecting section
detects an intensity of light incident thereon. In accordance with the
detection result obtained by the light detecting section, the respective
light intensities of the light-emitting sections disposed in the small
area are controlled.

[0142]Therefore, with the foregoing arrangement, it is possible to divide
the light-emitting area into the small areas and to adjust the light
intensities for each of the small areas.

[0143]As a result, it becomes possible to make an adjustment so that
brightness unevenness is suppressed for each of the small areas
constituting the light-emitting area. This makes it possible to reduce
brightness unevenness entirely in the light-emitting area.

[0144]In the foregoing arrangement, the backlight device according to the
present invention is preferably arranged so that: the light detecting
section detects respective light intensities of a plurality of color
components; and the light-emitting sections have the light intensities
that are controlled for a plurality of color components.

[0145]With the foregoing arrangement, the light detecting section detects
the respective light intensities of the plurality of color components,
and the light-emitting sections have the light intensities that are
controlled for the plurality of color components, respectively.

[0146]Therefore, the foregoing arrangement makes it possible to not only
adjust the light intensities in each of the small areas but also adjust a
color of light that is emitted in the small area.

[0147]This makes it possible to reduce color unevenness as well as uneven
brightness.

[0148]In the foregoing arrangement, for the purpose of carrying out the
foregoing control, it is only necessary to provide a control section for
controlling the respective light intensities of the light-emitting
sections in accordance with the detection result obtained by the light
detecting section.

[0149]In the foregoing arrangement, the backlight device according to the
present invention is preferably arranged so as to include substrates each
of which includes the light detecting section and the light-emitting
sections thereon and which are divided so as to respectively correspond
to the plurality of small areas.

[0150]According to the foregoing arrangement, since (i) the light
detecting section and (ii) the light-emitting sections that are
controlled in accordance with the detection result obtained by the light
detecting section are mounted on each of identical substrates, backlight
devices having light-emitting areas of various sizes can be easily
arranged by combining the substrates.

[0151]In the foregoing arrangement, the backlight device according to the
present invention is preferably arranged so that each of the substrates
has a shape similar to a shape of the light-emitting area.

[0152]A display area of an image display panel generally has a rectangular
shape having a predetermined aspect ratio. Therefore, when the substrate
has a shape similar to a shape of the display area, it becomes easy to
arrange backlights having light-emitting areas corresponding to display
areas of various sizes.

[0153]In the foregoing arrangement, the backlight device according to the
present invention is preferably arranged so that the substrate has
dimensions of 81 mm×144 mm.

[0155]In the foregoing arrangement, the backlight device according to the
present invention is preferably arranged so that: the plurality of
light-emitting sections are disposed in a matrix manner in each of the
small areas, and the light detecting section is provided in the small
area so as to be positioned such that: (i) a number of light-emitting
sections disposed in front of the light detecting section in a column
direction is equal to or different by one from a number of light emitting
sections disposed behind the light detecting section in the column
direction; and (ii) a number of light-emitting sections disposed in front
of the light detecting section in a row direction is equal to or
different by one from a number of light emitting sections disposed behind
the light detecting section in the row direction.

[0156]According to the foregoing arrangement, in each of the small areas,
the light detecting section is located substantially in the middle of the
plurality of light-emitting sections disposed in a matrix manner.
Therefore, it becomes possible to detect an average light intensity of
each of the small areas by using the light detecting section. This
enables a more appropriate adjustment.

[0157]In the foregoing arrangement, the backlight device according to the
present invention is preferably arranged so that: the substrate has a
surface, including the light-emitting sections thereon, which surface has
been subjected to a reflectance improving process. The reflectance
improving process refers to a process of improving a light reflectance of
the surface of the substrate, and is realized, for example, by (i)
applying a white resin onto the surface of the substrate or (ii) pasting
a high-reflectance sheet to the surface of the substrate.

[0158]According to the foregoing arrangement, the intensity of light that
is to be lost on the surface of the substrate is reduced. This makes it
possible that the light emitted from the light-emitting sections is used
more efficiently.

[0159]In the foregoing arrangement, the backlight device according to the
present invention is preferably arranged so that: each of the
light-emitting sections includes three types of light-emitting element
that emit red, green, and blue light, respectively.

[0160]According to the foregoing arrangement, brightness and/or color can
be adjusted by controlling respective outputs of the three types of
light-emitting element.

[0161]Note that at least one of the three types of light-emitting element
includes (i) a light source and (ii) a luminescent material which absorbs
light emitted from the light source and which emits light having a
wavelength longer than a wavelength of the light emitted from the light
source.

[0162]In the foregoing arrangement, the backlight device according to the
present invention is preferably arranged so that: at least one of the
three types of light-emitting element is a semiconductor light-emitting
element formed by using a semiconductor substrate made of silicon carbide
or gallium nitride, and is sealed with a transparent resin having an
index of refraction which lies between an index of refraction of the
semiconductor substrate and an index of refraction of air.

[0163]According to the foregoing arrangement, the transparent resin lies
on a path of light which is emitted from a light-emitting layer of the
semiconductor light-emitting element and which is sent out after
traveling through the semiconductor substrate. This allows a gradually
change in refractive index on the path leading from the semiconductor
substrate to the outside (air). This makes it possible to take out more
light from the path, so that the light can be used more efficiently.

[0164]In the foregoing arrangement, the backlight device according to the
present invention is preferably arranged so that a surface on which the
semiconductor light-emitting element is mounted is plated with silver.

[0165]According to the foregoing arrangement, the light which is emitted
from the light-emitting layer of the semiconductor light-emitting element
and which is sent to the surface on which the semiconductor
light-emitting element is mounted can be efficiently reflected by the
silver plating. Therefore, the light which is sent to the surface on
which the semiconductor light-emitting element is mounted becomes able to
be taken out efficiently, so that the light can be used more efficiently.

[0166]In the foregoing arrangement, the backlight device according to the
present invention is preferably arranged so that the light detecting
section includes a light-shielding section for preventing light emitted
from the light-emitting sections from being directly incident on the
light detecting section.

[0167]According to the foregoing arrangement, the light emitted from the
light-emitting sections falls indirectly on the light detecting section
(e.g., light diffused, for example, by the image display panel or a
diffusion plate provided in the image display panel falls on the light
detecting section), it becomes possible to detect light in a manner more
similar to observation via the image display panel.

[0168]In the foregoing arrangement, the backlight device according to the
present invention is preferably arranged so that: each of the substrates
has a temperature detecting section for detecting a temperature of the
substrate, and the light-emitting sections mounted on the substrate have
the respective light intensities that are further controlled in
accordance with a detection result obtained by the temperature sensor
mounted on the substrate.

[0169]According to the arrangement, it becomes possible to control the
respective light intensities of the red, green, and blue LEDs in
consideration of the fact that respective light-emitting states of the
red, green, and blue LEDs change due to a change in the temperature of
the substrate.

[0170]A display apparatus according to the present invention is arranged
so as to include: any one of the foregoing backlight devices; and a
non-self-luminous image display panel for displaying an image by
controlling a transmission state of light emitted from the backlight
device.

[0171]With the foregoing arrangement, it is possible to reduce brightness
unevenness on a display screen.

[0172]The present invention can be applied to a direct-type backlight
device used for a non-self-luminous image display panel such as a liquid
crystal panel.

[0173]The present invention is not limited to the description of the
embodiments above, but may be altered by a skilled person within the
scope of the claims. An embodiment based on a proper combination of
technical means disclosed in different embodiments is encompassed in the
technical scope of the present invention.

Embodiment 1 of the Second Invention

[0174]FIG. 13 is a diagram schematically showing a rear side of a liquid
crystal display apparatus 101 of the present embodiment. Each of a
plurality of tiles 112 has a front side on which a plurality of LED chips
104 (described later because they are not shown in FIG. 13) serving as
light-emitting elements are assembled. Light emitted from the LED chips
104 is uniformed by a diffusion plate 122 and illuminates a liquid
crystal panel 123 disposed outside of the diffusion plate 122, so that an
image can be displayed. The number of tiles 112 to be arranged
longitudinally and transversely can be freely determined depending on a
screen size of an LCD television. The present embodiment assumes that:
each of the tiles 112 has an aspect ratio of 8:9, and 8×4 (8 tiles
112 wide by 4 tiles 112 high) tiles 112 are disposed so as to be suitable
for an HDTV screen having an aspect ratio of 16:9. The backlight device,
disclosed in WO 00/037904 (published on Jun. 29, 2000), which uses a
waveguide plate has a backlight area that is not essentially divided, so
that it is difficult to divide, into four or more, a display area
corresponding to a sensor. On the other hand, since the present
embodiment can be divided into an arbitrary number of tiles, the present
embodiment is suitable for a large backlight device. In the display
apparatus, the liquid crystal panel 123 can be replaced by a
non-self-luminous image display panel other than a liquid crystal panel.
Examples of the non-self-luminous image display panel include an MEMS
(microelectromechanical system) panel and a shutter panel using an
electrooptic or electrophoretic effect.

[0175]Each of the tiles 112 has four sides, i.e., two opposite pairs of
sides. Two opposite sides of one of the two opposite pairs of sides are
respectively provided with connectors 113 for connecting the plurality of
tiles 112. A connector 113 of one tile 112 is connected to a connector
113 of another tile 112 by a cable 116. In this way, each of the tiles
112 is connected to a control substrate 124.

[0176]The control substrate 124 is provided with a microcomputer 111. The
microcomputer 111 serves as a control circuit for transmitting, to
integrated circuit elements 110 of the tile 112, signals based on which
LED driving is carried out.

[0177]FIG. 14(a) shows a surface of the tile 112. The tile 112 includes a
base substrate 112A made of glass epoxy, so that multilayer wiring is
possible. Provided in the center of the surface is a light sensor 102
made up of three photodiodes that respectively detect red, green, and
blue. The light sensor 102 is surrounded by an LED configuration region
103 in which a plurality of red LED chips, a plurality of green LED
chips, and a plurality of blue LED chips are die-bonded (the red, green,
and blue LEDs being collectively called "LED chips 104). By thus
disposing the light sensor 102 in the center of the tile 112, the light
sensor 102 is not much affected by light emitted from neighboring tiles.
Therefore, closed-loop feedback control can be carried out between the
light sensor 102 and the LED chips 104 inside the tile 112.

[0178]As shown in FIG. 14(b), the tile 112 has a rear surface on which the
integrated circuit elements 110 have been mounted. Each of the integrated
circuit elements 110 is connected to the outside via a connector 113 and
a cable 116. Further, a radiator plate 114 is provided so that a part
where the integrated circuit element 110 has been disposed is exposed.

[0179]FIG. 15 is a cross-sectional view of the tile 112. As shown in FIG.
15, on a surface of the base substrate 112A, (i) an electrode pad (not
shown) of each of the plurality of LED chips 104 and (ii) a wiring pad
provided in the tile 112 are wire-bonded by a gold wire 105 so as to be
electrically connected to each other. The LED chip 104 and the gold wire
105 are sealed with a transparent sealing resin 115. The radiator plate
114 is mounted on a rear surface of the base substrate 112A opposite the
LED chip 104. The radiator plate 114 has contact with a chassis 120
constituting part of the display apparatus (unit), so that heat is
radiated efficiently from the chassis 120. The rear surface of the base
substrate 112A has places which do not have contact with the radiator
plate 114 and on which the integrated circuit elements 110 have been
respectively mounted. Further, the rear surface of the base substrate
112A has two opposite sides on which the connectors 113 have been
respectively disposed.

[0180]FIG. 16 is an enlarged sectional view of the vicinity of a part
where the LED chip 104 has been die-bonded on the base substrate 112A.
Provided beneath a region where the LED chip 104 has been die-bonded is a
through hole 117. A wire 118 leads from the part where the LED chip 104
has been die-bonded, and reaches the rear surface of the base substrate
112A via the through hole 117. The wire 118 is made of a highly thermally
conductive metal such as copper, and is structured so as to have contact
with the radiator plate 114. This brings about a high effect of radiating
heat generated by the LED chip 104.

[0181]The present embodiment uses glass epoxy as a material of the base
substrate 112A. This enables multilayer wiring, so that the tile 112
becomes free from wiring restrictions. This makes it possible to ensure a
degree of freedom in terms of LED chip wiring. Since complex wiring
becomes possible, it becomes easy to mount the integrated circuit
elements 110 on the tile 112.

[0182]Note that some or all of the red, green, and blue LEDs used in the
present embodiment may be replaced, for example, as follows. That is,
each of the red LEDs may be replaced by a combination of (i) a blue LED
and (ii) a luminescent material that absorbs light emitted from the blue
LED and emits red light. Further, each of the green LEDs may be replaced
by a combination of (a) a blue LED and (b) a luminescent material that
absorbs light emitted from the blue LED and emits green light. Further,
it is possible to use a combination of (I) an LED that emits ultraviolet
light and (II) luminescent materials that respectively emit red, green,
and blue light.

[0183]Further, the present embodiment describes an example in which the
red, green, and blue LEDs are used as the light-emitting elements and in
which chromaticity and luminance are uniformed. However, for example,
white LEDs may be used as the light-emitting elements. In such a case, it
becomes unnecessary to carry out control concerning chromaticity, so that
only control concerning luminance is carried out. Examples of each of the
white LEDs may include a combination of a normal red LED and a yellow
luminescent material. However, preferred examples of the white LED
include the aforementioned combination of a blue LED and red and green
luminescent materials or the aforementioned combination of an ultraviolet
LED and red, green, and blue luminescent materials.

[0184](Circuit Arrangements and Operation of a Backlight Device in
Embodiment 1 of the Second Invention)

[0185]FIG. 17(a) is a diagram schematically showing a circuit arrangement.
Mounted in the tile 112 are the light sensor 102, the LED chips 104, and
the integrated circuit elements 110 (each of the integrated circuit
elements 110 being made up of an A/D converter 110A, a rewritable ROM
110B, and an LED driving circuit 110C). The light sensor 102 is a light
sensor covering a set made up of a photodiode having a red filter, a
photodiode having a green filter, and a photodiode having a blue filter.
The light sensor 102 detects respective light intensities of the red,
green, and blue LED chips 104 provided in the tile 112. Then, the light
sensor 102 transmits, to the A/D converter 110A, an analog signal
corresponding to the light intensities. The A/D converter 110A converts
the analog signal into a digital signal.

[0186]The rewritable ROM 110B stores an output value (hereinafter referred
to as "light sensor reference value") produced by the light sensor 102 in
cases where the LED chips 104 emit light having a predetermined
chromaticity and a predetermined luminance (the storage method will be
described later).

[0187]The backlight device operates as follows. That is, when the LED
chips 104 provided in each of the tiles 112 constituting the backlight
device are driven, the light sensor 102 detects chromaticity and
luminance within the tile 112, and (i) an output value of the light
sensor 102 and (ii) the light sensor reference value stored in the
rewritable ROM 110B are sent to the microcomputer 111 provided outside of
the tile 112.

[0188]The microcomputer 111 is used commonly for all the tiles 112. The
microcomputer 111 makes a comparison between (i) the output value of the
light sensor 102 and (ii) the light sensor reference value stored in the
rewritable ROM 110B, and standardizes the output value of the light
sensor 102. The standardization is carried out, for example, by carrying
out a calculation according to which the ratio between (i) the output
value of the light sensor 102 and (ii) the light sensor reference value
is obtained by dividing (i) the output value of the light sensor 102 by
(ii) the light sensor reference value. The microcomputer 111 generates
such a control signal that the standardized light sensor output thus
obtained approximates to a set value (chromaticity and luminance set by a
viewer of the liquid crystal display apparatus), and transmits the
control signal to the LED driving circuit 110C provided in the integrated
circuit element 110.

[0189]The LED driving circuit 110C controls, in accordance with the
control signal, the pulse width of a PWM (pulse width modulation) driving
current that is to be supplied to the LED chips 104. The present
embodiment produces the PWM output with an electrical current value held
constant, but it is possible to change luminance or chromaticity by
changing the electrical current value. Further, the PWM driving output
may be replaced by an analog output (an electrical current value at which
a required light intensity is obtained).

[0190]The microcomputer 111 mounted in the control substrate 124 sends the
control signal to the plurality of tiles 112 in a time-sharing manner.
The reason for this is that: the chromaticity and luminance of the
backlight are adjusted mainly for the purpose of making corrections with
respect to temperature changes or moment-to-moment changes, and it is not
necessary to continuously transmit the control signal.

[0191]By carrying out such an operation, feedback control of matching the
output value of the light sensor 102 to the set value is carried out.
Since the feedback control is carried out so that a standardized light
sensor output of each tile becomes constant, the chromaticity and
luminance of light-emitting elements of one tile may be different from
the chromaticity and luminance of light-emitting elements of another
tile. For example, a light sensor of a tile disposed in a central portion
of the backlight device receives much light from neighboring tiles. For
this reason, the luminance of light-emitting elements of the tile is
suppressed so that a standardized light sensor output of the tile becomes
constant. In this way, the backlight device operates so that uniform
luminance is obtained entirely in the backlight device.

[0192]According to the foregoing operation, the backlight device
constantly emits white light having a certain set value. However, a
feedback operation can be carried out also in cases where the set value
varies. For example, it is possible to make an adjustment in accordance
with a video signal used for liquid crystal display. A set value, for
obtaining white light, corresponding to the standardized light sensor
output is normally R:G:B=1:1:1. On the other hand, a set value, for
displaying a dark image as a whole, corresponding to the standardized
light sensor output is R:G:B=0.2:0.2:0.2. Alternatively, it is possible
to carry out an operation for adjusting chromaticity as well as
luminance. For example, in cases where a blue image (e.g., an image of
the sea) is displayed by using the tiles 112 of the liquid crystal
display apparatus, it is possible to carry out such an operation that the
standardized light sensor output is set at R:G:B=0.1:0.2:1.0.

[0193]Further, as shown in FIG. 14(b), the plurality of integrated circuit
elements 110 are mounted on the tile 112. However, it is not necessary
that all the integrated circuit elements 110 are identical. For example,
one of the integrated circuit elements 110 may be made up of the A/D
converter 110A, the rewritable ROM 110B, and the LED driving circuit
110C, and each of the remaining integrated circuit elements 110 may be
made up of an LED driving circuit 110C.

[0194]FIG. 17(b) is a diagram schematically showing a flow of signals in
another arrangement. Mounted in the tile 112 are the light sensor 102,
the LED chips 104, and integrated circuit elements 110Z (each of the
integrated circuit elements 110Z being made up of an A/D converter 110A,
a rewritable ROM 110B, an LED control circuit 110D, and an LED driving
circuit 110C).

[0195]The light sensor 102 detects respective light intensities of the
red, green, blue LED chips 104 provided in the tile 112, and transmits,
to the A/D converter 110A, an analog signal corresponding to the light
intensities. The A/D converter 110A converts the analog signal into a
digital signal.

[0196]The rewritable ROM 110B stores a light sensor reference value
corresponding to an output value produced by the light sensor 102 in
cases where the LED chips 104 emit light having a predetermined
chromaticity and a predetermined luminance. The light sensor reference
value and the output value of the light sensor 102 are sent to the LED
control 110D provided in the tile 112, and the LED driving circuit 110C
drives the LED chips 104 in accordance with a control signal transmitted
from the LED control circuit 110D.

[0197]The microcomputer 111 is used commonly for all the tiles 112. On
this occasion, the microcomputer 111 simply generates such a setting
signal that chromaticity and luminance each set by a viewer of the liquid
crystal display apparatus are obtained, and sends the setting signal to
the LED control circuit 110D provided in the integrated circuit element
110Z.

[0198]The LED control circuit 110D sends, to the LED driving circuit 110C,
such a control signal that a standardized light sensor output (i.e., the
ratio between (i) the signal obtained by the light sensor 102 and (ii)
the light sensor reference value) corresponds to a value that is based on
the setting signal. The LED driving circuit 110C controls, in accordance
with the control signal, the pulse width of a PWM (pulse width
modulation) driving current that is to be supplied to the LED chips 104.

[0199]Note that there is a question of whether or not feedback control can
be carried out only within a tile although a light sensor 102 of the tile
receives light from a neighboring tile. For example, in cases where the
luminance of the neighboring tile is actually low, the luminance of
light-emitting elements provided in the aforementioned tile inevitably
becomes higher than a predetermined value by carrying out feedback
control of compensating for the low luminance of the neighboring tile.
This raises such a problem that luminance unevenness increases. The same
is true of chromaticity. Moreover, as with the present embodiment, in a
structure in which one tile is not shielded from light emitted from
another tile, the light sensor 102 may receive more light from the
neighboring tile than from the aforementioned tile. However, in cases
where feedback control is carried out for each of the tiles of the
display apparatus, the chromaticity and luminance of the neighboring tile
are kept constant. Therefore, even when closed-loop feedback control is
carried out within such a tile, it is possible to correct variations in
chromaticity and luminance mainly within each of the tiles. This makes it
possible to carry out such feedback control that no unevenness occurs in
the entire backlight device.

[0200]Note that functional correspondence between (i) the arrangement
described in the present embodiment and (ii) the arrangement described in
the First Invention is as follows: the liquid crystal display apparatus
101 corresponds to the liquid crystal display apparatus 1; the liquid
crystal panel 123 corresponds to the liquid crystal unit 2; the
integrated circuit elements 110 of each of the tiles 112 correspond to
the backlight control section 5; the rewritable ROM 110B corresponds to
the reference light intensity data memory 51e; the microcomputer 111
corresponds to the control function of the driving and power supply
circuit 6; the tiles 112 correspond to the backlight substrates 31; the
light sensor 102 corresponds to the color sensor 31a; and the LED chips
104 correspond to LEDs 31b.

[0201](Method for Adjusting a Light Sensor Reference Value with Respect to
Each Tile in Embodiment 1 of the Second Invention)

[0202]The following explains how a light sensor reference value necessary
for obtaining a standardized light sensor output is set and how the light
sensor reference value is stored in the rewritable ROM 110B.

[0203]Each of the tiles 112 is placed into a tile adjusting apparatus 140
shown in FIG. 18. The tile adjusting apparatus 140 has an external light
sensor 142 for receiving light emitted from the plurality of LED chips
104 of the tile 112. Further, the tile adjusting apparatus 140 includes a
diffusion plate 145 for diffusing light emitted from the LED chips 104 of
the tile 112. The diffusion plate 145 is made of the same material as the
diffusion plate 122 used for the liquid crystal display apparatus 101.
The diffusion plate 145 is provided so that the distance between the tile
112 and the diffusion plate 145 is equal to the distance between the tile
112 and the diffusion plate 122. The external light sensor 142 used
herein is a sensor identical to the light sensor 102, but may be a sensor
different from the light sensor 102.

[0204]Whereas the light sensor 102 detects light reflected by the
diffusion plate 122, the external light sensor 142 detects light
transmitted by the diffusion plate 145. For this reason, respective
outputs of the light sensor 102 and the external light sensor 142 do not
correspond to each other. In light of this, the light sensor 102 and the
external light sensor 142 carry out detection at the same time under the
state in which the LED chips 104 emit light, and a coefficient of
correlation between respective outputs of the light sensor 102 and the
external light sensor 142. For the purpose of eliminating background
offset, respective outputs of the light sensor 102 and the external light
sensor 142 may be obtained under the state in which the LED chips 104 are
turned off, and the coefficient of correlation may be corrected by using
the outputs.

[0205]Note that the distance between the external light sensor 142 and the
tile 112 is preferably longer than the length of a diagonal line of the
tile 112, more preferably longer than the length of twice the diagonal
line of the tile 112.

[0206]An external control circuit 144 reads-in (i) values which are set in
an external memory 143 and which respectively correspond to a
predetermined chromaticity and a predetermined luminance and (ii)
detection values of the external light sensor 142 (Step 1A). The external
control circuit 144 sends, to the LED driving circuit 110C (see FIG.
17(a)) provided in the integrated circuit element 110, such a control
signal that the detection values of the external light sensor 142 become
equal respectively to the set values of the external memory 143, and the
LED driving circuit 110C drives all the LED chips 104 (Step 1B). The
external control circuit 144 receives an output produced by the light
sensor 102 at that time (Step 2A), and an operation of calculating a
value obtained through multiplication by the correlation coefficient
(i.e., calculating a light sensor reference value) is carried out (Step
2B). Then, the light sensor reference value is stored in the rewritable
ROM 110B (see FIG. 17(a)) provided in the integrated circuit element 110
(Step 3).

[0207]The predetermined chromaticity and the predetermined luminance may
be values obtained at one point where the luminance is high and the color
temperature is at a predetermined level (e.g., 9000K). Alternatively, the
predetermined chromaticity and the predetermined luminance may be values
obtained at a plurality of points, e.g., four points obtained by
combining the following cases (i) to (iv): (i) the luminance is high;
(ii) the luminance is low (e.g., one-fifth the high luminance); (iii) the
color temperature is high (e.g., 12000K); and (iv) the color temperature
is low (e.g., 5000K). Alternatively, the red, green, and blue LEDs do not
need to be driven at the same time. In such a case, an operation
including the following steps (1) to (3) is carried out with respect to
the red LED first. In the step (1), the external control circuit 144
reads out a predetermined luminance (low luminance, middle luminance,
high luminance) of the red LED from the external memory 143, and sends a
control signal to the driving circuit 110C so that a detection value of
the external light sensor 142 becomes equal to the predetermined
luminance, thereby driving the red LED (Step 1 concerning R). In the step
(2), the external control circuit 144 reads-in an output produced by the
light sensor 102 in the step (1), and calculates a value obtained through
multiplication by the correlation coefficient (i.e., calculates a light
sensor reference value) (Step 2 concerning R). In the step (3), the light
sensor reference value is stored in the rewritable ROM 110B provided in
the integrated circuit element 110 ep 3 concerning R). The same operation
may be carried out with respect to the green and blue LEDs. Such a
relatively small number of light sensor reference values may be stored,
and light sensor reference values that could be obtained under other
conditions may be made up by calculations. Alternatively, a large number
of light sensor reference values (e.g., values obtained at 256 points)
may be stored.

[0208]The tile adjusting apparatus 140 having the external light sensor
142 (or substantially the same tile adjusting apparatus arranged so as be
able to carry out the same adjustment as does the tile adjusting
apparatus 140) is commonly used for adjusting all the tiles 112, and a
light sensor reference value in each of the tiles 112 is stored in the
rewritable ROM 110B of the tile 112. With this, a backlight device having
excellent uniformity is obtained simply by combining the tiles 112
unadjusted. Further, for example, in cases where one tile 112 is damaged
in the backlight device, it is only necessary to replace the damaged tile
112 with a new tile 112. The new tile 112 thus mounted does not require
an adjustment, but can emit light identical to light emitted from a
neighboring tile. This makes it easy to carry out repairs.

Embodiment 2 of the Second Invention

[0209]Another problem is that it is difficult to carry out an adjustment
so as to obtain luminance uniformity or chromaticity uniformity within a
tile. For example, see a technique disclosed in United States Unexamined
Patent Publication No. 2006103612 (published on May 18, 2006). According
to the technique, a driving voltage and a duty ratio are stored for each
LED so that variations in luminance of the LED are corrected. In such a
case, luminance uniformity is obtained initially. However, the
luminescence intensity of the LED is inevitably changed when conditions
such as the temperature of the LED are changed. In cases where LEDs of a
plurality of colors are used, chromaticity uniformity is also lost.

[0210]The present embodiment not only sets chromaticity and luminance for
each tile but also uses means for obtaining light uniformity within each
tile substrate. Moreover, the present embodiment carries out feedback
control using a light sensor, so that light uniformity is not changed
even when a temperature change or the like occurs.

[0211]An effect of improving light uniformity is obtained also by
disposing a large number of small tiles. However, this causes an increase
in the number of parts such as light sensors. This results in high
production cost. Therefore, the present embodiment may be more
industrially applicable depending on the cost of the parts.

[0212]FIGS. 19(a) and 19(b) are front and rear views schematically showing
an arrangement of a tile 150, respectively. Mounted on a surface of the
tile 150 are: (i) red LED groups 151R, 152R, 153R, and 154R, each of
which includes red LEDs (each represented by "R" in FIG. 19(a)) connected
in series; (ii) green LED groups 151G, 152G, 153G, and 154G, each of
which includes green LEDs (represented by "G" in FIG. 19(a)) connected in
series; and (iii) blue LED groups 151B, 152B, 153B, and 154B, each of
which includes blue LEDs (represented by "B" in FIG. 19(a)) connected in
series; and (iv) a light sensor 155. Since the LEDs are thus connected in
series in each of the LEDs groups, it is only necessary to set, for the
LED group, a proportional coefficient serving as a correction value. It
is also possible that: the LEDs are not connected in series; and a
correction value is set for each of the LEDs; and the LEDs are driven
individually.

[0213]The LED groups 151R to 154B mounted on the surface of the tile 150
are connected, via through holes 158, to integrated circuit elements 157
mounted on a rear surface of the tile 150, respectively. The light sensor
155 is connected, via through holes 159, to an integrated circuit element
156 mounted on the rear surface of the tile 150.

[0214]A backlight device according to the present embodiment operates as
follows. First, LED groups 151R to 154B provided in each of tiles 150
constituting the backlight device are turned on. Light emitted from LEDs
provided in the tile and its neighboring tiles is reflected by a
diffusion plate 122 (same as that shown in FIG. 13), and is detected by a
light sensor 155. The light sensor 155 generates a light signal. The
light signal is sent to an A/D converter 156A provided in the integrated
circuit element 156. Then, the light signal is sent, via a connector 113,
to a microcomputer 111 (same as that shown in FIG. 13) provided outside
of the tile 150. On this occasion, the light signal is sent together with
a light sensor reference value stored in a rewritable ROM 156B provided
in the integrated circuit element 156.

[0215]The microcomputer 111 generates a control signal so that a
standardized light sensor output of the light sensor 155 becomes
constant. The control signal is sent to a correction circuit 157B
provided in each of the integrated circuit elements 157. The correction
circuit 157B (i) refers to data (described later) stored in a rewritable
ROM 157A storing a correction value, (ii) corrects the control signal,
and (iii) sends the corrected control signal to an LED driving circuit
157C. The LED driving circuit 157C drives, for example, the LED group
151R in accordance with the corrected control signal. The same is true of
the other LED groups 151G and 151B. The present embodiment considers the
LED groups 151R, 151G, and 151B to be one set, and drives the set of LED
groups 151R, 151G, and 151B by using the LED driving circuit 157C.
However, for example, it is possible to consider the LED groups 151R,
152R, 153R, and 154R to be one set and to provide a driving circuit for
the set of LED groups 151R, 152R, 153R, and 154R. It is also possible to
drive all the LED groups of the tile 150 by using a single LED driving
circuit. Further, the LEDs of each of the LED groups does not need to be
connected in series, but may be either connected in parallel or connected
both in series and in parallel. The LEDs do not need to constitute the
LED group, and each of the LEDs may be individually driven by a driving
circuit connected thereto.

[0216]By thus (i) driving each of the LED groups in accordance with a
control signal corrected for the LED group and (ii) carrying out feedback
control so that the standardized light sensor output becomes equal to a
predetermined value, it is possible to drive the backlight device which
emits light uniformly even within a tile.

[0217]The light sensor 155 may be made up of only one photodiode using no
filter. In this case, light emitted from the red LEDs, light emitted from
the green LEDs, and light emitted from the blue LEDs are detected as
follows. That is, during the operation of the backlight device, the light
emitted from the red LEDs is detected by the light sensor 155 within a
period of time set so that only the red LEDs are on and the LEDs of the
other colors are off. The detection is carried out in the same manner
with respect to the LEDs of the other colors, so that information
concerning chromaticity and luminance is obtained. The detection method
has an advantage of not being affected by deterioration in a filter.

[0218](Method for Adjusting a Light Sensor Reference Value and an LED
Group Correction Coefficient with Respect to Each Tile in Embodiment 2 of
the Second Invention)

[0219]As with Embodiment 1 of the Second Invention, the present embodiment
sets a light sensor reference value for the entire backlight device. In
addition, for the purpose of reducing variations within the tile 150, the
present embodiment carries out a setting of information (hereinafter
referred to as "LED group correction coefficient") corresponding to a
condition for driving each of the LED groups 151R to 154B so that each of
the LED groups 151R to 154B emits light having a predetermined luminance
or chromaticity. The setting is carried out as follows.

[0220]The tile 150 is placed into a tile adjusting apparatus 170 shown in
FIG. 20. The tile adjusting apparatus 170 includes: a diffusion plate 171
for diffusing light emitted from the LED groups 151R to 154B of the tile
150; and an area sensor 172 for detecting, as an image, variations in
chromaticity and luminance within the diffusion plate 171. The diffusion
plate 171 is made of the same material as the diffusion plate 122 used
for the liquid crystal display apparatus 101, and is provided so that the
distance between the tile 150 and the diffusion plate 171 is identical to
the distance between the tile 150 and the diffusion plate 122.

[0221]An external control circuit 174 sends a control signal to the
integrated circuit element 157 (Step 4A). The LED driving circuit 157C
turns on the LED groups 151R to 154B, so that the diffusion plate 171 is
illuminated. Then, the chromaticity and luminance of the diffusion plate
171 are detected by using the area sensor 172, and the external control
circuit 174 detects the ratios of the detection values to average values
(variations within the substrate) (Step 4B). For example, in cases where
a part, which is close to the LED groups 151R, 151G, and 151B, of the
diffusion plate 171 has a reddish color, a correction coefficient serving
as such a proportional coefficient that the driving output of the red LED
group 151R is reduced is written in the corresponding rewritable ROM 157A
(see FIG. 19(b)) (Step 5 concerning chromaticity). Further, for example,
in cases where the part, which is close to the LED groups 151R, 151G,
151B, of the diffusion plate 171 is darker than other parts of the
diffusion plate 171, such a correction coefficient that the respective
driving outputs of the LED groups 151R, 151G, and 151B are increased is
stored in the corresponding rewritable ROM 157A (Step 5 concerning
luminance).

[0222]The following explains how a light sensor reference value is stored
in a memory.

[0223]The external control circuit 174 reads-in (i) values which are set
in an external memory 173 so as to respectively correspond to a
predetermined chromaticity and a predetermined luminance and (ii)
detection values of the area light sensor 172 (Step 1A). The external
control circuit 174 sends, to the correction circuit 157B (see FIG.
19(b)) provided in the integrated circuit element 157, a control signal
so that the detection values of the area light sensor 172 become equal
respectively to the values set in the external memory 173 so as to
respectively correspond to the predetermined chromaticity and the
predetermined luminance. The correction circuit 157B (i) refers to data
stored in a rewritable ROM 157A storing a correction value, (ii) corrects
the control signal, and (iii) sends the corrected control signal to an
LED driving circuit 157C. The LED driving circuit 157C drives all the LED
groups 151R to 154B (Step 1B). Red, green, and blue outputs produced as
an image by the area sensor 172 are averaged, so that the area sensor 172
works as a mere light sensor.

[0224]An output produced by the light sensor 155 at that time is sent to
the external control circuit 174 (Step 2A), and a light sensor reference
value is calculated (Step 2B). Since the diffusion plate 171 is provided,
the output of the light sensor 155 corresponds substantially to an output
to be produced by the light sensor 155 actually incorporated into the
liquid crystal display apparatus 101. However, in cases where there is a
difference between the outputs, the difference is calculated. Then, the
light sensor reference value is calculated which is an output produced by
the light sensor 155 under the state in which the averaged detection
values become equal to the predetermined chromaticity and the
predetermined luminance.

[0225]Moreover, the light sensor reference value is stored in the
rewritable ROM 156B provided in the integrated circuit element 156 (see
FIG. 19(b)) (Step 3). Note that Steps 1 to 3 may be carried out for each
of the colors as described above.

[0226]Thus, the light sensor reference value is set after the LED group
correction coefficient has been set. With this, the adjustment is
simplified. The LED group correction coefficient may be set after the
light sensor reference value has been set. However, on this occasion, the
light sensor reference value may be misaligned. In such a case, the light
sensor reference value only needs to be set again.

[0227]The distance between the area sensor 172 and the diffusion plate 171
is preferably longer than the length of a diagonal line of the tile 150,
more preferably longer than the length of twice the diagonal line of the
tile 150.

[0228]In this way, a light sensor reference value of each tile 150 is
stored in a rewritable ROM 156B of the tile 150, and an LED group
correction coefficient of each tile 150 is stored in a rewritable ROM
157A of the tile 150. Then, the backlight device is driven in accordance
with the light sensor reference value and the LED group correction
coefficient. This makes it possible to obtain a backlight device in which
uniform chromaticity and uniform luminance are obtained both among tiles
and within a tile.

[0229]In the present embodiment, an LED group correction coefficient is
set for each LED group. However, for the purpose of emitting light more
uniformly, it is preferable that LEDs be driven individually and that a
correction coefficient be set for each of the LEDs. This corresponds to a
case where the number of LEDs provided in an LED group is 1.

Embodiment 3 of the Second Invention

[0230]In the present embodiment, integrated circuit elements 187 are
disposed on a surface of each of tiles 180. Further, LED groups are
disposed differently.

[0231]FIG. 21 is a cross-sectional view of the tile 180 according to the
present embodiment. Each of the integrated circuit elements 187 is
disposed on a surface of a base substrate 180A, and a high-reflectance
member 121 is provided so as to cover the integrated circuit element 187.
The high-reflectance member 121 has the following functions (1) and (2):
(1) the high-reflectance member 121 reflects light emitted transversely
from each of LEDs 104 constituting each of LED groups, in order that the
light is reflected upward; and (2) the high-reflectance member 121
re-reflects light returning from a diffusion plate 122 (not shown) to the
substrate. Further, connectors 113 and cables 116 that are used for
connecting the tiles 180 are also covered with the high-reflectance
member 121.

[0232]The tile 180 is structured so as to have a rear surface that has
direct contact with a chassis 120. With this, heat is radiated
efficiently.

[0233]FIG. 22 is a cross-sectional view obtained by enlarging part of FIG.
21. Provided beneath a region where the LED chip 104 has been die-bonded
is a through hole 117 that leads to a multilayer wire 118 provided on a
rear surface of the base substrate 180A. Further, provided directly below
a region where the integrated circuit element 187 has been die-bonded is
also a through hole 117 that leads to the multilayer wire 118 provided on
the rear surface of the tile 180. The multilayer wire 118 has direct
contact with the chassis 120. With this, heat due to the LED chip 104 and
the integrated circuit element 187 is guided to the multilayer wire 118
via each of the through holes 117, so that the heat can be radiated from
the chassis 120 to the outside.

[0234]FIG. 23 is a diagram schematically showing the surface of the tile
180. Mounted on the surface of the tile 180 are: (i) red LED groups 181R,
182R, 183R, and 184R, each of which includes red LEDs connected in
series; (ii) green LED groups 181G, 182G, 183G, and 184G, each of which
includes green LEDs connected in series; and (iii) blue LED groups 181B,
182B, 183B, and 184B, each of which includes blue LEDs connected in
series; and (iv) a light sensor 185. The LED groups 181R, 181G, and 181B,
the LED groups 182R, 182G, and 182B, the LED groups 183R, 183G, and 183B,
and the LED groups 184R, 184G, and 184B, which are combinations of red,
green, and blue LED groups, are respectively disposed in the four
quadrants of the tile 180, and are disposed axisymmetrically both in a
longitudinal direction and in a transverse direction with respect to the
light sensor 185.

[0235]A backlight device using the tile operates as follows. When each of
the LED groups is driven, the light sensor 185 generates a light signal.
The light signal is sent to an A/D converter 186A provided in an
integrated circuit element 186. Then, together with a light sensor
reference value stored in a rewritable ROM 186B provided in the
integrated circuit element 186, the light signal is sent, via a connector
113, to a microcomputer 111 (not shown) provided outside of the tile 180.
The microcomputer 111 generates a control signal corresponding to a
predetermined luminance and a predetermined chromaticity, and the control
signal is sent to a correction circuit 187B provided in the integrated
circuit element 187 mounted on the surface of the tile 180. The
correction circuit 187B (i) refers to data stored in a rewritable ROM
187A storing an LED group correction coefficient, (ii) corrects the
control signal, and (iii) sends the corrected control signal to an LED
driving circuit 187C. The LED driving circuit 187C drives, for example,
the LED groups 181R in accordance with the corrected control signal. The
same is true of the other LED groups 181G and 181B. With this, the
luminance and chromaticity are held constant within the tile, and
feedback control of correcting variations within the tile is carried out.
The same control is carried out in neighboring tiles. With this, the
backlight device operates as a backlight device having uniform luminance
and uniform chromaticity.

[0236](Method for Adjusting a Light Sensor Reference Value and an LED
Group Correction Coefficient with Respect to Each Tile in Embodiment 3 of
the Second Invention)

[0237]As with Embodiment 1 of the Second Invention, the present embodiment
sets a light sensor reference value for the entire backlight device.
Unlike Embodiment 2 of the Second Invention, the present embodiment do
not use an area sensor. For the purpose of reducing variations within the
tile 180, the present embodiment sets an LED group correction coefficient
for each of the LED groups 181R to 184B. The setting is carried out as
follows.

[0238]The tile 180 and a diffusion plate 191 are placed into a tile
adjusting apparatus 190 shown in FIG. 24. A lid 190A is closed so that
the tile 180 and the diffusion plate 191 are placed in a dark place. The
diffusion plate 191 is supported by rails 191A. Provided on an upper
surface of the tile adjusting apparatus 190 is an external light sensor
192.

[0239]An external control circuit 194 sends, to driving circuits 187C (see
FIG. 23) of four integrated circuit elements 187, control signals for
turning on red LED groups 181R, 182R, 183R, and 184R, respectively (Step
A concerning R), so that the diffusion plate 191 is illuminated. The
external control circuit 194 reads-in the chromaticity and luminance of
the diffusion plate 191 from the external light sensor 192, and detects
the ratios of the read-in values to average values (variations within the
substrate) (Step 4B concerning R). The external control circuit 194
inputs, to each of respective rewritable ROMs 187A (see FIG. 23) of the
four integrated circuit elements 187, an LED group correction coefficient
serving as a proportional coefficient for obtaining a driving output
identical to an output produced by the external light sensor 192 in Step
4B (Step 5 concerning R).

[0240]The same correction coefficient inputting operation is carried out
with respect to green LED groups 181G to 184G and blue LED groups 181B to
184B.

[0241]After the foregoing operation, the external control circuit 194
reads-in (i) set values of an external memory 193 and (ii) output values
of the external light sensor 192 (Step 1A concerning R). Then, the
external control circuit 194 controls a lighting of the red LED groups
181R to 184R so that the output values of the external light sensor 192
become equal respectively to the set values of the external memory 193
(Step 1B concerning R). Then, the external control circuit 194 obtains an
output value of the light sensor 185, and calculates a light sensor
reference value (Step 2 concerning R). Then, the external control circuit
194 writes the light sensor reference value in a rewritable ROM 186B (see
FIG. 23) provided in an integrated circuit element 186 (Step 3 concerning
R). This operation is carried out for the LED groups of each of the
colors. In this case, for the purpose of calculating the light sensor
reference value, a correlation between (i) an output produced by the
light sensor 185 within the tile adjusting apparatus 190 and (ii) an
output produced by the light sensor 185 actually provided in a liquid
crystal apparatus is calculated in advance.

[0242]By carrying out the foregoing adjustment with the diffusion plate
191 inserted, a value close to a value of an output produced by the light
sensor 185 incorporated into a liquid crystal display apparatus is
obtained. Under some conditions, the foregoing calculation can be omitted
(it is conceivable to carry out a calculation using a coefficient of 1).
However, the foregoing adjustment can be carried out even under the state
in which the diffusion plate 191 has been removed.

Other Possible Embodiments of the Second Invention

[0243]According to each of the foregoing embodiments, a single tile is
made up of a single base substrate and other components. However, a tile
only needs to be able to be treated as a single entity. Therefore, for
example, a single tile may include: a first substrate; a second substrate
attached onto a rear surface of the first substrate; and an integrated
circuit and the like disposed on the second substrate.

[0244]Suppose, for example, there is a single tile including a total of
four tiles (2×2 tiles (2 tiles wide by 2 tiles high)) according to
the foregoing embodiment. In such a case, there are four sensors that are
not disposed in the center of the single tile. However, this is
essentially no different from the foregoing embodiment.

[0245]Further, the foregoing embodiment does not use a temperature sensor.
However, an LED chip, especially a red LED chip, has a wavelength that
varies with the temperature. Therefore, the luminance in view of
visibility may not be stabilized simply by stabilizing the light
intensity. For the purpose of compensating for this point, a temperature
sensor is used, and LED driving output may be corrected in accordance
with a detection value of the temperature sensor.

[0246]Further, the foregoing embodiment uses a rewritable ROM as a memory.
However, a one-time writable ROM, a flash memory, or a RAM backed up by a
battery may be used.

[0247]Further, the foregoing embodiment assumes that light sensors are
used in all of the tiles. However, light sensors may be mounted only on
some of the tiles.

[0248]The present invention is not limited to the description of the
embodiments above, but may be altered by a skilled person within the
scope of the claims. An embodiment based on a proper combination of
technical means disclosed in different embodiments is encompassed in the
technical scope of the present invention.

[0249]The embodiments and concrete examples of implementation discussed in
the foregoing detailed explanation serve solely to illustrate the
technical details of the present invention, which should not be narrowly
interpreted within the limits of such embodiments and concrete examples,
but rather may be applied in many variations within the spirit of the
present invention, provided such variations do not exceed the scope of
the patent claims set forth below.